This is a companion executable to go along with plug and playground https://github.com/fakob/plug-and-play, it solves CORS issues and deals with authentication to API's.
It can read environmental variables or a file ".env" adjacent to the executable, so you can put your API keys there, anything matching the format ${MYVARIABLENAME} in the call from PNP will be replaced.
Check releases for binaries.