Trying to wrap my head around 2FA... Any help?

I really like Ente Auth, because of its end-to-end encrypted sync (your codes are encrypted on-device before they ever touch the cloud, and only you hold the decryption key), it is well maintained (actively developed as part of the ente ecosystem, open-source with audited crypto, and regularly updated), and it’s 100 % FLOSS with a clean F-Droid build.

f-droid.org

Ente Auth - 2FA Authenticator | F-Droid - Free and Open Source Android App...

Free, Cross Platform, Private, Open Source Two Factor Authenticator App