Aegis is a good one for Android. I use the totp field in my keepassdx database that I open with a password (or fingerprint) and my yubikey to store my auth codes. I use this with syncthing running on a raspberry pi so it syncs the password database across my phone and all my computers.
Edit: initially said keepassXC I meant keepassdx for the mobile app. Xc is the desktop version.
here’s a decent list of some public server instances you can look into. Tells you where they are located, if there are any rules or a privacy policy, what version of the server they’re running, and some other stuff like that
https://joinmatrix.org/servers/