Setting up Guix for your hardware could be challenging if any of its components (like wifi adapter) does not support free firmware. Setting up them may require onfiguring 3rd party channels and that would need time and patience at first. Any Guix official mailing list or its IRC channel does not provide any support for nonfree hardware, so this could be also a challenge for you at the beginning stage.

I have not used NixOS, so can’t compare (in terms of other than GNU philosophy). But I took help of NixOS to write some package definitions for myself.

By the way, within Guix I can also run a nix-daemon (if I want).

The battery of the device is gone. EDIT: I read it wrong. Not the power daemon, but the battery device is broken.