It's viable because all of the important components are open source. That's the entire genius of open source, if you're capable enough then you're immune to future changes. You can fork a project and take over development. It only costs developers and that's well within the budget of a modern western country.

Any country who is going to undertake the effort to move away from Windows will have the resources to support distros which align with their country's interest or create their own. Even North Korea has their own distro of Linux, I'm sure the EU countries can find the talent required to ensure their software meets their needs.

As an individual, you're right. You're largely at the whims of the people who volunteer their time to the kernel, the software ecosystem and the individual distributions. If you have infinite money then those problems become a line item in your budget.