I search a two factor authentication OTP app for Android that fullfills these demands:
- Google authenticator compatible
- TOTP at least
- protection by PIN or similar
- export function
I'd recommend you andOTP – which is gratis and free, support TOTP, is compatible with Google authenticator, offers protection by pin, password and even fingerprint – and also comes with an export function (in form of plain-text or encrypted backups); and thus meets all your requirements.