I get the feeling that privacy advocates like the German CCC or the EFF in the US need to get ahead of this chat control and age verification bullshit by implementing a privacy-first age verification system prototype. Something where you can identify yourself as adult that is both trustworthy and anonymous.
Because if they don't, palantir will implement your age verification and harvest all your data.
That'd work too, although I'd implement it the other way around. Define a new http header that indicates what type of content the site you're visiting is hosting and handle the content blocking client-side based on those headers.