The crypto involved can be furnished such that nothing but the issuing authority and the fact “18+” gets transmitted, no name, no id number, no nothing.
This is a best-case-scenario implementation. I just think it is extremely likely that any approach actually implemented would not have the privacy of the user in mind.
+1 for Pop. I fully expected to distro hop but have had it on my main rig for over a year now. Surprisingly pleasant.