Something I have never understood is why the hard-on with Nix, and Guix is not heard of even a tenth of the times. Is GPL really so repulsive to the masses? Or the libre kernel default?
I use guix myself and prefer its use of scheme. I don't mind having a little less guidance and "how-to" articles available if I'm trying something new because I'm comfortable reading its codebase.
FWIW Nix does not allow unfree packages by default or, at least, that's what having to add a package to allowUnfreePredicate makes it feel like.