> I think this is why they effectively only target x64
Nix and Nixpkgs is the best in class when it comes to cross platform & cross architecture support. It has good support for x86_64 / aarch64 /macOS / Linux. Getting Musl or static variants of existing packages just work for many packages. There's even some work on BSD / Windows support. Cross compiling is far easier to setup compared to other package managers. If anything, other projects should be copying what Nix is doing.
NetBSD's pkgsrc has always done extremely well for me for that.
I'm not sure how feasible it would be to compare nixpkgs and pkgsrc given how different they are, but I'd encourage people who need that to poke around at both and see which one feels like a better fit for their use case.
Nix and Nixpkgs is the best in class when it comes to cross platform & cross architecture support. It has good support for x86_64 / aarch64 /macOS / Linux. Getting Musl or static variants of existing packages just work for many packages. There's even some work on BSD / Windows support. Cross compiling is far easier to setup compared to other package managers. If anything, other projects should be copying what Nix is doing.