Privacy
Screen lock
App lock on the device. It is not a backup of the recovery phrase and not a second set of keys.
GreyWallet includes screen-lock / app-security controls so the open app is not available to whoever picks up the phone. That lock is local. It does not back up the phrase. It does not move keys off-device. It does not replace Private Vaults.
If you forget the app lock, that is a device-access problem. It is not a reason to send a phrase to support. If you forget the recovery phrase, the wallet is not recoverable regardless of screen lock.