The petition is open to all EU resident. The goal is to replace all Windows in all public institution in Europe with a sovereign GNU/Linux.
If the petition is successful it would be a huge step forward for GNU/Linux adoption.
Basically everyone in the community agrees that Mint, Ubuntu and Fedora are the best choices for new users. Mint and Ubuntu are pretty similar, so they don’t require separate maintenance effort, and supporting Fedora is not that hard, if you already support RHEL, CentOS or another rpm-based distro (which are pretty common in the enterprise space). For all the desktop applications, Flatpak exists and is agreed on as the standard format by most of the desktop Linux community.