Canonical is UK based, so scrub that.
But Redhat, Rocky, Alma are all owned by US legal entities and can absolutely be legally forced to do as you describe.
Technically blocked is something else, mind. We're clever, resourceful and motivated people and US laws wouldn't directly affect us.
However - you're thinking small. US influence of IT is massive. Routers, servers, hardware of all levels. The most enterprise level software is US led. All of these things can be restricted, or tarriffed heavily, or sanctioned entirely. If the US wants to hurt the rest of the world, it just has to tell Broadcom to turn off vmware outside of America. Ditto Cisco, Ditto Dell, Ditto... etc etc. Sure, it would be illegal, but does the American government care about that?
Anyone telling you that "Y won't happen because it's unthinkable" clearly hasn't been paying attention this year.