There was some proposal from California or something to require OSs to enforce age verification, it was discussed in some other thread.

For what it's worth, the "verification" in the California law (not a bill, it's already passed and takes effect 2027) is basically the Steam birthdate popup interstitial. There's explicitly no actual link to any outside information, just requiring that the system save a value the user sets and then that apps use that value for any age gating.