I have gnome-authenticator and its dependencies (pyfavicon, pyzbar and yoyo) backported to amber-phone locally on my phone already, just need to push it out and set up CI.
It's also already in byzantium.
gnome-authenticatior already is packaged in Debian, but it is an old version; 3.32
And in pureos as well:
gnome-authenticator/byzantium,landing 3.32.2+dfsg1-2 all TOTP authentication app for the GNOME Desktop