+1 on AndOTP.
It's also available on f-droid [1] and of course open source [2].
[1]: https://f-droid.org/en/packages/org.shadowice.flocke.andotp/
I'd even recommend Aegis [1]. Also open source with encrypted backups, but has better crypto than andOTP (both devs talk a bit about it here [2]). Plus, it can do imports from other OTP apps for easy migration.
[1] https://github.com/beemdevelopment/Aegis
[2] https://old.reddit.com/r/androidapps/comments/b45zrj/dev_aeg...
Thanks for this, I really like the discourse between these two in the second link. The andOTP author is open about their crypto being sub-optimal and giving the Aegis dev a thumbs up, reason enough for me to give Aegis a shot to replace it. Perhaps they'll join forces going forward and we all win. :)
Where are you storing those backups? If it's the same place as the passwords, you're weakening the second-factor assumption.
https://play.google.com/store/apps/details?id=org.shadowice....