I don't use NixOS myself, but have Nix installed on my Mac, and it seems to provide all functionality of package or version managers I needed.

I think though it is more complex because it is a programming language that provides this functionality instead of purpose build tool like asdf.

For my needs I created a framework for development: https://github.com/takeda/nix-cde to avoid cruft of including the same things over and over in my projects.