Who do they think writes Linux? The European Commission? They’re on the US tech stack whether they want to be or not, and nobody in Europe has the will or resources to pull a China and make their own alternative. More’s the pity.
But that's besides the point. The point is no company owns linux so you're not tied to big tech even if they are the biggest contributors to the kernel.
We may see Canonical or other commercial Linux vendors come forward with a government or enterprise-flavored solution for all this. But the important thing to keep in mind is that they're not selling Linux per-se. As the GPL prohibits this, these companies sell support for their Linux distro instead. That revenue goes into improving Linux and maintaining their distro (e.g. Ubuntu). But even with all that money changing hands, that they do not own Linux, the Linux kernel, or any other shred of GPL licensed stuff.