Limerance

Public key cryptography and signatures are common technologies nowadays.

It is possible to build an age verification system, where you use your actual ID with a cryptographic process without any personal data. The technology has existed for decades now.

As a user the license doesn’t matter for you. Even if you contribute back to a project, you will be able to use your changes in the project.

The license only matters if you want to redistribute a changed version yourself or use parts of it in your own software.