For everyone trying to figure out how this would be enforced, it's not about being proactively enforced. (and data collection is 99% of it)
It's about adding a double-tap "Well, these people also violated our age verification law, so they have to pay a fine," added to any incident where it's convenient to add this in. If a minor sends another minor a snap that would trigger CP laws, and one of the phones isn't age verified correctly, fine to the parents and hands up in the air "We tried!" A minor is involved in torrenting movies? "Look, kids using illegal OS! Fine to the parents!"
This is how laws work across a lot of corrupt developing countries. There's laws for everything, but they only get applied selectively as authorities find they fit the situation. It's hard to actually be 100% above board and do everything legally because of a few little things meant to be impossible to actually do bureaucratically. So in every situation, any set of authorities start in with the endemic leverage of "Well, we have suspicion of you selling ketamine out of your apartment. Did you do age verification on your laptop? No? Then we can seize that as a crime and see what's on there. OR you can give up your supplier."