Guix the package manager, while still not usable at work for me (lack of MacOS support - just 4 of my eng org's ~25 folks use Linux), is full of interesting ideas and features that work well in Linux settings, and can do useful things. It could make interesting dev shells, for example, much like nix-shell (or Flakes).
GuixSD without `nonguix`? Yeah, I unfortunately share your "it's dead in the water" opinion here. I'm not aware of much, if any, modern hardware that can fully boot to a usable-framerate GUI with networking (and that is also safe to use for such) without at least linux-firmware, which I believe is only available in nonguix. If there's exceptions to this, I'd genuinely love to hear them in a thread here.