Guix indeed doesn’t include nonfree software by default, but you can add the nonguix channel which does have it.

Unexpected advantage of NixOS here, I didn’t realize you could bisect right with your package manager this way! I would have just downgraded back to the 5.15 releases.

Did you report the issue upstream? I’m sure they’d be happy with the faulty commit already being identified.

A more European-focused alternative is ObsIdentify. Its image recognition for flora and fauna works especially well in the Netherlands and Belgium, for which it was originally developed, but it should work in the rest of Europe as well.