I agree with first one. We want application fingerprint authorization. It's a very essential feature nowadays
Nokia 5 using Stock OS , means its free from all the customizations. Suggest you to look up 3rd party applications for your specific needs.
1. App Locker - I'm using 'Norton App locker'. It unlocks using fingerprint and is free from ads. Its pretty smooth and no distractions, main reason for using this application.
4. Really don't advise you to not use RAM cleaners on Android as the tasks can auto-start and in turn drain the battery.
An app that closes the screen and unlocks the phone with a fingerprint and does do not ask the password?