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.
That Linux has to have this? B. S. There’s no way that could be enforced. Make every edition an alpha testing release. Make it not work. Whatever you have to do. Just don’t capitulate and immediately do their exact bidding.