AFAIK there are designs in the EU that respect privacy. There is a range of options being pushed around the world, and theres definitely a few of them which are more technically defensible than others.
The app also requires that you first send your personal information to a closed source backend, in exchange for easily trackable tokens used as "proof".
Do you have a link where I could read more about this? GrapheneOS is known for being the alternative Android where many bank apps in the EU still work, and this is the first I have heard that the age verification app definitely wouldn’t run on GrapheneOS.