For those interested on the question of age verification and GNU/Linux: be aware that Systemd v261-rc1 was recently released. It now implements an optional birth date field in the JSON user database (see second item under “Other changes”).
The implementation of this field was prompted by age-verification or -attestation laws.
There are genuinely useful use cases for it, and unlike what you suggest it is completely harmless.
Not invested enough to be for or against it personally; just curious…
What are the user-beneficial use cases for it?