This extension is added by Chris Andreae for MoErgo.
Nix makes setup significantly easier. With this approach West is not needed. You can however still choose to use the ZMK's sanctioned West if you wish.
In ZMK root directory,
nix-build -A *target* [-o *output_directory*]
An example is nix-build -A glove80_left -o left
The output_directory nix creates is a symlink. If you prefer not to rely on symlink (perhaps because you are using WSL on Windows), the following would help
cp -f $(nix-build -A *target* --no-out-link)/zmk.uf2 .
In ZMK root directory, cp -f $(nix-build -A glove80_combined --no-out-link)/glove80.uf2 .
Edit default.nix and add an target based on zmk
An example is:
glove80_left = zmk.override {
board = "glove80_lh";
};