That's true, but them doing a lot of the work predates the sovereignty announcement. I think that, in reality, no one actually knows what they're going to do. Instead, people found the Linux distros the French government technology office already made and wrote extrapolated news stories from there on the assumption that they weren't going to make yet another French government Linux distro.

I think it's a likely that this is true but it's hard to say for sure what will actually happen before the French government makes a formal announcement.

If I had to personally guess, you might see NixOS in security-critical roles and Ubuntu on people's office productivity machines.