This appears to be what Aylo think, essentially:

https://www.aylo.com/assets/files/age_verification_fact_shee...

And I think this is right. If Apple and Google can add a thing that lets us track Covid exposure they can surely figure out secure age attestation.

As it is, you can use your mobile phone for simple age attestation in the UK anyway, since mobile phone companies block adult content by default until they are unblocked, as a parental control measure.