It's hard for me to see how it could be done without unacceptable exposure. So, right now, it's the opposite of desirable to me and I would avoid using any sites that require it.
I imagine the problem is more economics and politics than technology. Say, personhood verification becomes available. Then it is also that much easier to mandate age verification, and that becomes a slippery slope.
Check age of persons but not personhood. How old are LLM's?
How do we check? Ask for a cookie recipe? What person can do that from memory?
