Thanks for the info.
Yeah, we are still trying to figure out the balance between sticking to NixOS specifics and duplicating upstream documentation (though it looks like it is lacking in this case). But I would say the relevant NixOS docs do contain the basics. Only really missing is the program name (but when user is using GUI, they will most likely launch it using the application launcher), and the mention of web store (which we need to discourage since many extension there require some kind of patching to work on NixOS).