The issue is not just age verification but also device pinning.

I think the framework here is to have community driven age verifiers( i recall there is an EU effort for digital wallets which besides it's bad parts has some of these good parts) which can verify ages for people and link them to( local biometrically encrypted) devices for pinning. This would be privacy preserving. The only downside is a mandate for all devices have a built-in hardware biometric encryption like a finger/face print so phones can't be just(used) with these apps installed.

The verification part is a job that could be done by all the teachers and coaches and ofc parents. Any one verifying identities would be cryptographically nominated/revoked by a number of more senior members of the community. A prent always get the right to say ok for their kid ofc but so could teachers or legal guardians..

We(legally) need a mandate for smart devices to have local device only biometric verification. The law should be to have these apps follow device app store protocols.