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.
A surprising amount of people in the open source community lean alt-right including the lead dev of systemd, some of FUTO, and others like hyprland, etc. Others like the actual dev that committed the age field code to systemd state they are apolitical but in reality are actually enabling those that want to do harm.