Any kind of zero knowledge verification should be ok.
But with minors it often goes a long way to just make the law. It’s a good instruction to parents who should be able to control this. Laws on bike helmets for minors are followed nearly 100% not because they are enforced by authorities but because the law gives parents guidance.
Bike helmets are for safety but reading the article the ban is more for some kind of societal change. I don’t know if it’s really comparable.
There is no such thing in practice.
Anything with zero knowledge is never going to be considered robust enough by a government. Zero knowledge protocols really have no functional revocation mechanism.