Except systemd isn't an OS. xdg-desktop-portal is not an OS. None of these projects need to flop over and acquiesce to this overreach.

This is optional functionality which a subset of their important customers want. You will continue to have options that do not make use of this feature.

As someone with children, I see benefits in how age verification will help me manage my kids relationship with technology. Even if it was not the law, I would choose products with support. The point of open source is to allow for both options.