The Guix zealotry will be their undoing, and frankly this is where Nix shines. I can use Nix at work, at home, with family, with vendors, with binary blobs, on macOS. The community tries very hard to help.
With Guix, sure, there's stuff like nonguix, but take a gander at this from the nonguix readme:
> Please do NOT promote this repository on any official Guix communication channels, such as their mailing lists or IRC channel, even in response to support requests! This is to show respect for the Guix project’s strict policy against recommending nonfree software, and to avoid any unnecessary hostility.
Guix has truly noble goals (in classic GNU fashion) but they're ultimately misguided. Yes sure it's great that it's pure and reproducible and whatever else but if I can't get stuff done with it it's useless. Actually useless.
The standard encouraged response to "Hi I'm a new Guix user and I was wondering how I can run steam?" is roughly equivalent to "Go fuck yourself" and I'm just amazed by that.
If Guix ever becomes mainstream, it will be in spite of their efforts.
In the meantime, I'm betting on Nix.