I didn't follow the drama, i tried NixOS for a while and I like the concept but in practice it isn't 100% Linux, it's an abstraction and if a software isn't supported you are fucked.
You have to know the nix language to setup a system; the same language builds packages for the package manager (one of or maybe the most expansive package manager across linux). It's not hard to build packages. Pop a nix file in your repo, and anyone can pull & use your app nix style. Submit a PR and it'll be included in the main public package repo cache.