Comment by copirate

One thing I love about NixOS is how easy it is to run packages from different sources. For example, I needed an old package that's been removed from nixpkgs several years ago. To run it I just had to add an old release of nixpkgs as input to my flake.nix and add the package from this input. It pulls all its dependencies from that old release and there's zero conflict with the other packages.