I'm not sure if you work in software or not, but it's definitely possible to come up with a schema where you could verify people's age in order to use a platform, without exposing your entire identity to said platform, with a combination of signatures and other cryptographic basics.
Say you have a digital certificate from the government or similar that you use to do your taxes online or whatever, the government could have endpoints where you could use that certificate for signing a proof, that you then hand over to the platform you want to verify your age with. The platform can then confirm it's valid, and that $AGE>X, but they get no other details.
You can even go a bit fancier/more complicated, and the government endpoints wouldn't know what platform you're trying to verify.
Say you have a digital certificate from the government or similar that you use to do your taxes online or whatever, the government could have endpoints where you could use that certificate for signing a proof, that you then hand over to the platform you want to verify your age with. The platform can then confirm it's valid, and that $AGE>X, but they get no other details.
You can even go a bit fancier/more complicated, and the government endpoints wouldn't know what platform you're trying to verify.