I was looking into Nix and Guix for the past week and it's a sad state of affairs.
It's such a cool concept but I ran across one sysadmin comment that turned me off from ever using either in production builds.
If the build goes wrong, are you confident enough you'll be able to fix it?
Looking at the complexity behind the nix scripting language and the lack of package management organiziation within guix (as well as Nix, they basically get packages broken every other day) there's no way I could be bothered to learn it.
The only reason to learn either is to flex people on your dotfile start up scripts, which you only run once every three years unless you're a kleptomaniac of your own bank account getting a new computer every year. Even then, just a year.
https://blog.cmpxchg8b.com/2020/07/you-dont-need-reproducible-builds.html
https://discourse.nixos.org/t/nixpkgss-current-development-workflow-is-not-sustainable/18741
Guix is objectively cooler than Nix but (and respectfully but) their integrity limits its spread and the packages available. I think there is a nonfree guix branch.
Just a scatter of thoughts from an onlooker; I may be wrong in some of my statements here.