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.
Wayland takes a lot of abuse but it is a great example of what is great about FOSS. Completely proprietary software could never abide that level of disruption.
If being driven by a minor player, it is just too hard and too risky. A commercial player with the economic dominance to pull it off would never see enough financial benefit to bother.
Take Windows. Even though modern Windows is from the “New Technology” branch of the Windows family, the security model was flawed with all users commonly running as Admin. Instead of really changing that, they have introduced a couple layers of duct tape ( eg. UAC ) but not fundamentally fixed it.