There's a fairly non-invasive way to do age verification: ID cards that connect to a smartphone app that only provide a boolean age verification to the requesting service. Requesting service can be anonymous to the ID app and the requesting service can only receive a bool.
That most implementation will try to collect far more data is the real concern.
The goal isn't child protection but surveillance and profits for kyc companies.
There's an even easier one: When you buy a phone, the salesman checks your ID and sets the phone to child lock mode or unlocked mode.
Phones should have no locks unless the user installs them and holds the keys.
Why?
Because if we don't have the keys to the machine, then we don't actually own our computers. If we don't own our computers, then we have no freedom.
Because everything the word "hacker" ever stood for will be destroyed if this nonsense gets normalized. The day governments get to decide what software "your" computer can run is the day it's all over.