I know, I even mentioned it. Unfortunately and understandably Guix means my WiFi won't work and there will be less stuff supported OOTB. So I'll be on Nix for foreseeable future.
You can include community sources in order to use the standard, non-libre Linux kernel - though my Guix experience was a bit frustrating in part due to complications such as this one compared to what I'm currently experiencing with NixOS (thoroughly enjoying it!).
There are a fair few very vocal former NixOS users who miss no opportunity to extol the benefits of Guix in the chatrooms I frequent, though. Not without merit either, I should say: the project and its UX does seem to be much more well-thought out; it's developed by GNU; the project takes software freedom seriously; many will surely enjoy hacking away at their config in Scheme. As it stands currently, though, there are more resources and it's easier to get things done with NixOS - you also get to use learn a (imo really great) packaging system that is in somewhat wide use.