A suggestion I would find extremely helpful on the app would to be total screentime limits. In my head, this would work where once you reach a certain amount of screentime (chosen by the user, or able to be fully disabled) would lock apps on the phone. It could also give warnings before this time is reached, saying that you have x amount of time left before your phone locks. It would help a lot personally to help me push myself for lower screentime without making it only app-specific, as I often lose track of my screentime making it hard to lower.
Thank you!