diff --git a/src/libstore/common-ssh-store-config.cc b/src/libstore/common-ssh-store-config.cc
index e1448b4b4eb..a2d7e2ebad6 100644
--- a/src/libstore/common-ssh-store-config.cc
+++ b/src/libstore/common-ssh-store-config.cc
@@ -9,28 +9,29 @@ namespace nix {
 CommonSSHStoreConfig::Descriptions::Descriptions()
     : Store::Config::Descriptions{Store::Config::descriptions}
     , CommonSSHStoreConfigT<config::SettingInfo>{
-        .sshKey{
-            .name = "ssh-key",
-            .description = "Path to the SSH private key used to authenticate to the remote machine.",
-        },
-        .sshPublicHostKey = {
-            .name = "base64-ssh-public-host-key",
-            .description = "The public host key of the remote machine.",
-        },
-        .compress = {
-            .name = "compress",
-            .description = "Whether to enable SSH compression.",
-        },
-        .remoteStore{
-            .name = "remote-store",
-            .description = R"(
-              [Store URL](@docroot@/store/types/index.md#store-url-format)
-              to be used on the remote machine. The default is `auto`
-              (i.e. use the Nix daemon or `/nix/store` directly).
+          .sshKey{
+              .name = "ssh-key",
+              .description = "Path to the SSH private key used to authenticate to the remote machine.",
+          },
+          .sshPublicHostKey{
+              .name = "base64-ssh-public-host-key",
+              .description = "The public host key of the remote machine.",
+          },
+          .compress{
+              .name = "compress",
+              .description = "Whether to enable SSH compression.",
+          },
+          .remoteStore{
+              .name = "remote-store",
+              .description = R"(
+                [Store URL](@docroot@/store/types/index.md#store-url-format)
+                to be used on the remote machine. The default is `auto`
+                (i.e. use the Nix daemon or `/nix/store` directly).
             )",
-        },
-    }
-{}
+          },
+      }
+{
+}
 
 const CommonSSHStoreConfig::Descriptions CommonSSHStoreConfig::descriptions{};
 
diff --git a/src/libstore/dummy-store.cc b/src/libstore/dummy-store.cc
index c6dd71ba669..968c2d3fbac 100644
--- a/src/libstore/dummy-store.cc
+++ b/src/libstore/dummy-store.cc
@@ -36,7 +36,7 @@ struct DummyStoreConfig : virtual StoreConfig {
         return {"dummy"};
     }
 
-    std::shared_ptr<Store> openStore() override;
+    std::shared_ptr<Store> openStore() const override;
 };
 
 
@@ -100,7 +100,7 @@ struct DummyStore : public virtual DummyStoreConfig, public virtual Store
     { unsupported("getFSAccessor"); }
 };
 
-std::shared_ptr<Store> DummyStore::Config::openStore()
+std::shared_ptr<Store> DummyStore::Config::openStore() const
 {
     return std::make_shared<DummyStore>(*this);
 }
diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index cbbb0fe7a34..ce296668798 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -715,7 +715,7 @@ struct curlFileTransfer : public FileTransfer
     }
 
 #if ENABLE_S3
-    std::tuple<std::string, std::string, Store::Params> parseS3Uri(std::string uri)
+    std::tuple<std::string, std::string, StoreReference::Params> parseS3Uri(std::string uri)
     {
         auto [path, params] = splitUriAndParams(uri);
 
diff --git a/src/libstore/http-binary-cache-store.cc b/src/libstore/http-binary-cache-store.cc
index b15ef4e4cba..0a663ec036d 100644
--- a/src/libstore/http-binary-cache-store.cc
+++ b/src/libstore/http-binary-cache-store.cc
@@ -3,6 +3,7 @@
 #include "globals.hh"
 #include "nar-info-disk-cache.hh"
 #include "callback.hh"
+#include "store-registration.hh"
 
 namespace nix {
 
@@ -12,7 +13,7 @@ MakeError(UploadToHTTP, Error);
 HttpBinaryCacheStoreConfig::HttpBinaryCacheStoreConfig(
     std::string_view scheme,
     std::string_view _cacheUri,
-    const Params & params)
+    const StoreReference::Params & params)
     : StoreConfig(params)
     , BinaryCacheStoreConfig(params)
     , cacheUri(
@@ -35,10 +36,10 @@ std::string HttpBinaryCacheStoreConfig::doc()
 }
 
 
-class HttpBinaryCacheStore : public virtual HttpBinaryCacheStoreConfig, public virtual BinaryCacheStore
+class HttpBinaryCacheStore :
+    public virtual HttpBinaryCacheStoreConfig,
+    public virtual BinaryCacheStore
 {
-private:
-
     struct State
     {
         bool enabled = true;
@@ -49,15 +50,14 @@ class HttpBinaryCacheStore : public virtual HttpBinaryCacheStoreConfig, public v
 
 public:
 
-    HttpBinaryCacheStore(
-        std::string_view scheme,
-        PathView cacheUri,
-        const Params & params)
-        : StoreConfig(params)
-        , BinaryCacheStoreConfig(params)
-        , HttpBinaryCacheStoreConfig(scheme, cacheUri, params)
-        , Store(params)
-        , BinaryCacheStore(params)
+    using Config = HttpBinaryCacheStoreConfig;
+
+    HttpBinaryCacheStore(const Config & config)
+        : Store::Config{config}
+        , BinaryCacheStore::Config{config}
+        , HttpBinaryCacheStore::Config{config}
+        , Store{static_cast<const Store::Config &>(*this)}
+        , BinaryCacheStore{static_cast<const BinaryCacheStore::Config &>(*this)}
     {
         diskCache = getNarInfoDiskCache();
     }
@@ -207,6 +207,10 @@ class HttpBinaryCacheStore : public virtual HttpBinaryCacheStoreConfig, public v
     }
 };
 
-static RegisterStoreImplementation<HttpBinaryCacheStore, HttpBinaryCacheStoreConfig> regHttpBinaryCacheStore;
+std::shared_ptr<Store> HttpBinaryCacheStore::Config::openStore() const {
+    return std::make_shared<HttpBinaryCacheStore>(*this);
+}
+
+static RegisterStoreImplementation<HttpBinaryCacheStore> regHttpBinaryCacheStore;
 
 }
diff --git a/src/libstore/http-binary-cache-store.hh b/src/libstore/http-binary-cache-store.hh
index d2fc43210a2..d15c6e3d0db 100644
--- a/src/libstore/http-binary-cache-store.hh
+++ b/src/libstore/http-binary-cache-store.hh
@@ -4,9 +4,8 @@ namespace nix {
 
 struct HttpBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
 {
-    using BinaryCacheStoreConfig::BinaryCacheStoreConfig;
-
-    HttpBinaryCacheStoreConfig(std::string_view scheme, std::string_view _cacheUri, const Params & params);
+    HttpBinaryCacheStoreConfig(
+        std::string_view scheme, std::string_view cacheUri, const StoreReference::Params & params);
 
     Path cacheUri;
 
@@ -25,6 +24,8 @@ struct HttpBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
     }
 
     std::string doc() override;
+
+    std::shared_ptr<Store> openStore() const override;
 };
 
 }
diff --git a/src/libstore/local-binary-cache-store.cc b/src/libstore/local-binary-cache-store.cc
index dcc6affe4a1..8fb163e3064 100644
--- a/src/libstore/local-binary-cache-store.cc
+++ b/src/libstore/local-binary-cache-store.cc
@@ -2,6 +2,7 @@
 #include "globals.hh"
 #include "nar-info-disk-cache.hh"
 #include "signals.hh"
+#include "store-registration.hh"
 
 #include <atomic>
 
@@ -10,7 +11,7 @@ namespace nix {
 LocalBinaryCacheStoreConfig::LocalBinaryCacheStoreConfig(
     std::string_view scheme,
     PathView binaryCacheDir,
-    const Params & params)
+    const StoreReference::Params & params)
     : StoreConfig(params)
     , BinaryCacheStoreConfig(params)
     , binaryCacheDir(binaryCacheDir)
@@ -26,21 +27,18 @@ std::string LocalBinaryCacheStoreConfig::doc()
 }
 
 
-struct LocalBinaryCacheStore : virtual LocalBinaryCacheStoreConfig, virtual BinaryCacheStore
+struct LocalBinaryCacheStore :
+    virtual LocalBinaryCacheStoreConfig,
+    virtual BinaryCacheStore
 {
-    /**
-     * @param binaryCacheDir `file://` is a short-hand for `file:///`
-     * for now.
-     */
-    LocalBinaryCacheStore(
-        std::string_view scheme,
-        PathView binaryCacheDir,
-        const Params & params)
-        : StoreConfig(params)
-        , BinaryCacheStoreConfig(params)
-        , LocalBinaryCacheStoreConfig(scheme, binaryCacheDir, params)
-        , Store(params)
-        , BinaryCacheStore(params)
+    using Config = LocalBinaryCacheStoreConfig;
+
+    LocalBinaryCacheStore(const Config & config)
+        : Store::Config{config}
+        , BinaryCacheStore::Config{config}
+        , LocalBinaryCacheStore::Config{config}
+        , Store{static_cast<const Store::Config &>(*this)}
+        , BinaryCacheStore{static_cast<const BinaryCacheStore::Config &>(*this)}
     {
     }
 
@@ -127,6 +125,6 @@ std::set<std::string> LocalBinaryCacheStoreConfig::uriSchemes()
         return {"file"};
 }
 
-static RegisterStoreImplementation<LocalBinaryCacheStore, LocalBinaryCacheStoreConfig> regLocalBinaryCacheStore;
+static RegisterStoreImplementation<LocalBinaryCacheStore> regLocalBinaryCacheStore;
 
 }
diff --git a/src/libstore/local-binary-cache-store.hh b/src/libstore/local-binary-cache-store.hh
index 997e8ecbb51..01f7969eb61 100644
--- a/src/libstore/local-binary-cache-store.hh
+++ b/src/libstore/local-binary-cache-store.hh
@@ -4,9 +4,12 @@ namespace nix {
 
 struct LocalBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
 {
-    using BinaryCacheStoreConfig::BinaryCacheStoreConfig;
-
-    LocalBinaryCacheStoreConfig(std::string_view scheme, PathView binaryCacheDir, const Params & params);
+    /**
+     * @param binaryCacheDir `file://` is a short-hand for `file:///`
+     * for now.
+     */
+    LocalBinaryCacheStoreConfig(
+        std::string_view scheme, PathView binaryCacheDir, const StoreReference::Params & params);
 
     Path binaryCacheDir;
 
@@ -18,6 +21,8 @@ struct LocalBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
     static std::set<std::string> uriSchemes();
 
     std::string doc() override;
+
+    std::shared_ptr<Store> openStore() const override;
 };
 
 }
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index aff70589d18..d3677fdeb39 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -113,7 +113,7 @@ std::string LocalStoreConfig::doc()
         ;
 }
 
-std::shared_ptr<Store> LocalStore::Config::openStore()
+std::shared_ptr<Store> LocalStore::Config::openStore() const
 {
     return std::make_shared<LocalStore>(*this);
 }
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 06e402f80f9..45cb04b7159 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -56,9 +56,6 @@ struct LocalStoreConfig :
 
     static const Descriptions descriptions;
 
-    /**
-     * The other defaults depend on the choice of `storeDir` and `rootDir`
-     */
     static LocalStoreConfigT<config::JustValue> defaults;
 
     LocalStoreConfig(const StoreReference::Params &);
@@ -75,7 +72,7 @@ struct LocalStoreConfig :
 
     std::string doc() override;
 
-    std::shared_ptr<Store> openStore() override;
+    std::shared_ptr<Store> openStore() const override;
 };
 
 class LocalStore :
diff --git a/src/libstore/machines.cc b/src/libstore/machines.cc
index 256cf918892..9e4145e0ac5 100644
--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@@ -1,6 +1,6 @@
 #include "machines.hh"
 #include "globals.hh"
-#include "store-api.hh"
+#include "store-open.hh"
 
 #include <algorithm>
 
diff --git a/src/libstore/misc.cc b/src/libstore/misc.cc
index bcc02206bc9..31762f34d2c 100644
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@@ -3,7 +3,7 @@
 #include "derivations.hh"
 #include "parsed-derivations.hh"
 #include "globals.hh"
-#include "store-api.hh"
+#include "store-open.hh"
 #include "thread-pool.hh"
 #include "realisation.hh"
 #include "topo-sort.hh"
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index 1a0ec11112e..abd2727194b 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -1,7 +1,5 @@
 #if ENABLE_S3
 
-#include <assert.h>
-
 #include "s3.hh"
 #include "s3-binary-cache-store.hh"
 #include "nar-info.hh"
@@ -187,6 +185,75 @@ S3Helper::FileTransferResult S3Helper::getObject(
     return res;
 }
 
+    const Setting<std::string> profile{
+        this,
+        "",
+        "profile",
+        R"(
+          The name of the AWS configuration profile to use. By default
+          Nix will use the `default` profile.
+        )"};
+
+    const Setting<std::string> region{
+        this,
+        Aws::Region::US_EAST_1,
+        "region",
+        R"(
+          The region of the S3 bucket. If your bucket is not in
+          `us–east-1`, you should always explicitly specify the region
+          parameter.
+        )"};
+
+    const Setting<std::string> scheme{
+        this,
+        "",
+        "scheme",
+        R"(
+          The scheme used for S3 requests, `https` (default) or `http`. This
+          option allows you to disable HTTPS for binary caches which don't
+          support it.
+
+          > **Note**
+          >
+          > HTTPS should be used if the cache might contain sensitive
+          > information.
+        )"};
+
+    const Setting<std::string> endpoint{
+        this,
+        "",
+        "endpoint",
+        R"(
+          The URL of the endpoint of an S3-compatible service such as MinIO.
+          Do not specify this setting if you're using Amazon S3.
+
+          > **Note**
+          >
+          > This endpoint must support HTTPS and will use path-based
+          > addressing instead of virtual host based addressing.
+        )"};
+
+    const Setting<std::string> narinfoCompression{
+        this, "", "narinfo-compression", "Compression method for `.narinfo` files."};
+
+    const Setting<std::string> lsCompression{this, "", "ls-compression", "Compression method for `.ls` files."};
+
+    const Setting<std::string> logCompression{
+        this,
+        "",
+        "log-compression",
+        R"(
+          Compression method for `log/*` files. It is recommended to
+          use a compression method supported by most web browsers
+          (e.g. `brotli`).
+        )"};
+
+    const Setting<bool> multipartUpload{this, false, "multipart-upload", "Whether to use multi-part uploads."};
+
+    const Setting<uint64_t> bufferSize{
+        this, 5 * 1024 * 1024, "buffer-size", "Size (in bytes) of each part in multi-part uploads."};
+
+
 S3BinaryCacheStore::S3BinaryCacheStore(const Params & params)
     : BinaryCacheStoreConfig(params)
     , BinaryCacheStore(params)
@@ -201,11 +268,6 @@ S3BinaryCacheStoreConfig::S3BinaryCacheStoreConfig(
     , BinaryCacheStoreConfig(params)
     , bucketName(bucketName)
 {
-    // Don't want to use use AWS SDK in header, so we check the default
-    // here. TODO do this better after we overhaul the store settings
-    // system.
-    assert(std::string{defaultRegion} == std::string{Aws::Region::US_EAST_1});
-
     if (bucketName.empty())
         throw UsageError("`%s` store requires a bucket name in its Store URI", uriScheme);
 }
diff --git a/src/libstore/s3-binary-cache-store.hh b/src/libstore/s3-binary-cache-store.hh
index 7d303a115f4..c28e9320378 100644
--- a/src/libstore/s3-binary-cache-store.hh
+++ b/src/libstore/s3-binary-cache-store.hh
@@ -7,87 +7,40 @@
 
 namespace nix {
 
-struct S3BinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
+template<template<typename> class F>
+struct S3BinaryCacheStoreConfigT
 {
-    std::string bucketName;
-
-    using BinaryCacheStoreConfig::BinaryCacheStoreConfig;
-
-    S3BinaryCacheStoreConfig(std::string_view uriScheme, std::string_view bucketName, const Params & params);
+    const F<std::string> profile;
+    const F<std::string> region;
+    const F<std::string> scheme;
+    const F<std::string> endpoint;
+    const F<std::string> narinfoCompression;
+    const F<std::string> lsCompression;
+    const F<std::string> logCompression;
+    const F<bool> multipartUpload;
+    const F<uint64_t> bufferSize;
+};
 
-    const Setting<std::string> profile{
-        this,
-        "",
-        "profile",
-        R"(
-          The name of the AWS configuration profile to use. By default
-          Nix will use the `default` profile.
-        )"};
+struct S3BinaryCacheStoreConfig :
+    virtual BinaryCacheStoreConfig,
+    S3BinaryCacheStoreConfigT<config::JustValue>
+{
+    struct Descriptions :
+        virtual Store::Config::Descriptions,
+        virtual BinaryCacheStore::Config::Descriptions,
+        S3BinaryCacheStoreConfigT<config::SettingInfo>
+    {
+        Descriptions();
+    };
 
-protected:
+    static const Descriptions descriptions;
 
-    constexpr static const char * defaultRegion = "us-east-1";
+    static S3BinaryCacheStoreConfigT<config::JustValue> defaults;
 
-public:
+    S3BinaryCacheStoreConfig(
+        std::string_view uriScheme, std::string_view bucketName, const StoreReference::Params & params);
 
-    const Setting<std::string> region{
-        this,
-        defaultRegion,
-        "region",
-        R"(
-          The region of the S3 bucket. If your bucket is not in
-          `us–east-1`, you should always explicitly specify the region
-          parameter.
-        )"};
-
-    const Setting<std::string> scheme{
-        this,
-        "",
-        "scheme",
-        R"(
-          The scheme used for S3 requests, `https` (default) or `http`. This
-          option allows you to disable HTTPS for binary caches which don't
-          support it.
-
-          > **Note**
-          >
-          > HTTPS should be used if the cache might contain sensitive
-          > information.
-        )"};
-
-    const Setting<std::string> endpoint{
-        this,
-        "",
-        "endpoint",
-        R"(
-          The URL of the endpoint of an S3-compatible service such as MinIO.
-          Do not specify this setting if you're using Amazon S3.
-
-          > **Note**
-          >
-          > This endpoint must support HTTPS and will use path-based
-          > addressing instead of virtual host based addressing.
-        )"};
-
-    const Setting<std::string> narinfoCompression{
-        this, "", "narinfo-compression", "Compression method for `.narinfo` files."};
-
-    const Setting<std::string> lsCompression{this, "", "ls-compression", "Compression method for `.ls` files."};
-
-    const Setting<std::string> logCompression{
-        this,
-        "",
-        "log-compression",
-        R"(
-          Compression method for `log/*` files. It is recommended to
-          use a compression method supported by most web browsers
-          (e.g. `brotli`).
-        )"};
-
-    const Setting<bool> multipartUpload{this, false, "multipart-upload", "Whether to use multi-part uploads."};
-
-    const Setting<uint64_t> bufferSize{
-        this, 5 * 1024 * 1024, "buffer-size", "Size (in bytes) of each part in multi-part uploads."};
+    std::string bucketName;
 
     const std::string name() override
     {
@@ -102,11 +55,13 @@ public:
     std::string doc() override;
 };
 
-class S3BinaryCacheStore : public virtual BinaryCacheStore
+struct S3BinaryCacheStore : virtual BinaryCacheStore
 {
+    using Config = S3BinaryCacheStoreConfig;
+
 protected:
 
-    S3BinaryCacheStore(const Params & params);
+    S3BinaryCacheStore(const Config &);
 
 public:
 
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index 7e9a5fa53f5..6571fd37c10 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -154,7 +154,7 @@ struct StoreConfig :
      * Open a store of the type corresponding to this configuration
      * type.
      */
-    virtual std::shared_ptr<Store> openStore() = 0;
+    virtual std::shared_ptr<Store> openStore() const = 0;
 };
 
 class Store : public std::enable_shared_from_this<Store>, public virtual StoreConfig