My experience from parenting two children to adulthood and being way too lax about devices led me to roughly the following rules for the rest of my kids:

1. Absolutely no phones in bed at any point of the day. Dpublecheck at bedtime that the phone is where it's supposed to be.

2. I vet every app on the phone.

3. Web browser is whitelisted.

4. I vet every contact on signal/whatsapp. No other messaging apps.

5. When they get access to a computer, I let them know that I can know everything they do with it. Also, the computer is stationary in a central place in the house.

When they complain that their friends have more rights, I will lament the unfortunate situation where I cannot dictate the rules of other families.

I'll obviously revise these rules as they grow and I get the feeling that they can handle it. The default mode for parents must always be that they can not.