This is the technology behind the digital wallet/age verification app. A challenge with these systems is that card readers that actually support this kind of thing are excessively rare and expensive for what they do, especially when used with desktops.

My German isn't that great, but I can't find any sources that state that the German eID can use ZKPs directly. From what I can tell, it uses basic signatures, and the new/upcoming wallet app will take care of ZKP generation. But maybe I'm missing a source in German?