> But if has to be embedded into the OS

that would be fine if the embedding means all applications can leverage this functionality - like how accessibility is embedded into the OS rather than per-app.

The only problem is if this embedding requires third-party verification (which i dont believe it is), or require some sort of hardware attestation to a remote server (so you cannot modify the OS to turn it off if you wish as a non-parent).

To me, flexibility and choice is paramount. The parents have the responsibility to monitor their child, and this tool should help when the parents opt-in for it. It should not be enforced on all computer users arbitrarily without a parental opt-in first.