When I used Guix, I needed nonfree for Firefox and the upstream Linux kernel. I also prefer to only use free software, and also like them not including proprietary software.

Needing a channel was a huge inconvenience as you would often pull your channels and stuff would break, as guix was updated but non-guix wasn't. Managing channel manifests was a pain. Firefox would often be months out of date as well.

Moved to NixOS, didn't enable allowUnfree, and had an actually up to date and simple to maintain system. Flakes solves the channels problems too. I had put a lot of effort into making Guix work, but it just had too many usabiltity issues, and the policy on firefox was a major one.