Aegis seems like a pretty good 2FA app on Android from what I’ve heard. Personally, I use Ente Auth as sync is very helpful when I don’t have my phone nearby (you can either use the desktop app or use your browser, both work). Don’t think you can self-host sync, though I might be wrong. Ente Auth also works without sync, so there’s that.

I would not suggest using a password manager’s 2FA integration (e.g. Bitwarden, I think Proton Pass has one if you use that?) as it kind of defeats the point of 2FA, since if someone got access to your password manager, they would also get the 2FA codes.