What authenticator app do you use? How do you backup? Any open source self hosted options?
keepass (xc/dx) and aegis
For iOS I use Raivo. https://apps.apple.com/us/app/raivo-otp/id1459042137
I use Aegis, which automatically backs up with each change to the database to a folder that gets synced to a couple of different computers via syncthing.
For backup codes, I have a separate keypass database that’s backed up to a couple of places. I thought about using Bitwarden for this backup, but having my 2FA backups in the same place as my passwords kinda defeated the point, IMO.
Anyway, this system has worked well for me.
I use the TOTP option in KeePassXC and KeePassDX to handle 2FA duties. I backup the encrypted file to my Nextcloud. If you self host Nextcloud or something similar this is a viable option.