Funnily enough there is some level of control that can be exerted by the US gov via the distros (at least the major ones - see legalese restrictions on Redhat/Ubuntu etc when you want to download , stating the various US gov laws/sanctions that they follow) and also via the kernel - i think some time back Russian kernel maintainers were removed.
So Open source it may be , however there are still pressure points that can be used. I believe this is one of the main reasons RISCV foundation moved to Europe.
Europe has a major distro in the form of SUSE, so that’s not too worrying.
Even if upstream linux banned european contributors, there are enough european contributors that a fork would just emerge. So I’m really not too worried about that happening.
Two if you mean Europe more generally, as Ubuntu is British.
Of the over 400 distros listed on DistroWatch.com, 79 are based in the United States.