That would be an interesting approach, but browsers are easily switched (to a “jailbroken” one) and I wouldn’t trust windows with such information… Linux would be fine, but I guess the linux community would at least be torn on this one (though I might ofc be wrong)
TL;DR Most people are against a age verification where you would input your personal ID or credit card. Adding a popup would be nice though (if it doesn’t already exist)
Thinking about all the included responsibilities, legislation, etc. gives me headache so I will not bother setting up a NSFW instance, from which thought the question originated… Thats propably why there isn’t a good one right now