Good suggestions but I’m not convinced that’s true.
It’s certainly possible to lock some Android devices down hard without rooting them. See Samsung Knox as an example. Even a pro will have a hard time getting around that.
I trust my kids to mostly only use the devices how I say. The security is mainly to keep their mum happy and to keep them from spur of the moment bad descisions with their clicks and time.
No, I don’t think it’s unreasonable to have a technical level of control over young kids devices in partnership with close supervision. It’s that or no phones until they’re 16.