nix does all three of these, I think.
Nix has better cross-compilation support is a little bit better than its native support, in terms of cross-platform coverage. But even then, I think, pkgsrc's platform coverage is in a different league. :)
Do you have more information?
> Nix is currently supported on the following platforms:
> - Linux (i686, x86_64, aarch64).
> - macOS (x86_64).
sh install-nix-2.3.10 install-nix-2.3.10: sorry, there is no binary distribution of Nix for your platform
What platform are you hoping to build Nix on?