Guix is also a great project and I don't want to dissuade anyone from using it, but Nix can also be used as a package manager only.
Does it allow you to install/run graphical apps that require GPU access? That's my biggest annoyance right now with using Nix packages on my Debian (stable) system, they just don't work for everything.
You can often set up /run/opengl-driver to mirror NixOS and it will work. For instance for CUDA: