EID can be used for anonymous age verification. It doesn’t even need to give out your birthday and can attest to any “over the age of X” requirement.

Ref: https://www.bfdi.bund.de/DE/Buerger/Inhalte/Telematik-Statistik-Verkehr-Bildung/Meldewesen-Statistik/Der_Personalausweis.html

So use whatever you were using before and add that as an external library to immich?

https://immich.app/docs/features/libraries