I think I'm heading to the place were you already are. I gave access to phones to my kids, and all the apps that monitor their time fail, when there is no will in them to stop. Also doing any task with the phone makes them navigate away (to instant messaging with their colleagues etc)

But on the other hand - the world is digital now. I have no idea how to make them learn good habits on finding things on the internet while not falling to the infinite well of doomscrolling etc.