One more step to unhitching from Google…
Right now the only option I see in F-Droid is Aegis.
I’m not sure what to actually look for side from checking for unexpected permissions and reasonably frequent updates.
Hopefully something I can sync with a GNOME app…
FreeOTP/FreeOTP+
depending on your goal for this (real 2fa vs just simulated) you shouldn’t have sync in the first place.
you could also look into security keys (hardware solution, webauthn/FIDO2) as an alternative that has strong security with good user experience (no typing anymore), but they’re not as widely accepted.