like, the most extreme form of this I could imagine would be "you need to obtain a certificate/license of successful training in Internet and perhaps pay a regular fee to be able to access most/all of the internet, otherwise you only get a very narrowed-down version (even if you could reach the servers, the servers would also be forced by law by default to deny you access w/o the cert".
That's not technically impossible to implement.
In fact, it would be way easier to implement than the "ban social media for kids+teenagers" stuff considered currently.
You just need to either get buy-in or force social media providers, VPN providers and ISPs to implement that.
Sure, it would massively restrict access for most people. But what if you just would have to buy a device in a store to get access to a VPN to view "adult content", and you need to show an ID to buy it. (similarly, make SIM cards age-gated; they often already require ID).
It's easy (both in implementation and policy, and easily enforceable after a grace period), devastating in impact, and most critique of age-gating or whatever curr. considered wouldn't apply.
actually, if the weird bans itself can't be prevented, this approach would be imo one of the best possible implementations.
Maybe I'm a bit biased. Germans love their overlay networks. Just look at Gematik, DN42, etc. (this is perhaps the most hilarious list I've ever made)