How to Add Unfree Packages?

[AngleSideAngle]

I was trying to contribute a collection of packages that I regularly use to this repository, including nonfree software. However, I ran into quite a bit of difficulty figuring out how to incorporate some kind of configuration for enabling nonfree packages since nixpak/pkgs is a flake. I'm not very experienced with nix, so I would appreciate guidance on how to pragmatically do this.

The idea I've been trying to implement was adding this functionality to a module in flake.nixosModules.default, since then config.allowUnfree could be set by the user. I can't seem to figure out how to do this though, since builders.mkNixPakPackage is defined inside a perSystem attribute, and all my attempts to move it have resulted in infinite recursion errors for reasons beyond my comprehension.

Any advice would be appreciated :)

[max-privatevoid]

I'd rather not have unfree software in this repo since I build all the flake outputs in CI and then provide them on my publicly accessible binary cache.

[AngleSideAngle]

That's understandable. Perhaps they could be in a separate repository?