I do not expect that I could ever trust the 3rd party. And any on-device "private solution" seems unlikely to be implemented in a provably secure and safe way.

I do not expect that I could ever trust the 3rd party. And any on-device "private solution" seems unlikely to be implemented in a provably secure and safe way. Besides that, why is any of that complicated stuff even needed? I know my age, and I am able to verify my age without involving any 3rd party, software, AI etc. If someone else wants to lie about their age, I am not convinced that I should need to jump through hoops and give away my own privacy as part of any of the flawed schemes supposedly intended to prevent that, as some governments are trying to push.