Imagine a country in which Republican states are free to do this, while you are free to pursue UHC in Democrat states. Obviously only the most extreme States would be able to pass them.
HOWEVER,
One of these methods is better than the other. If yours is as sucessful as you pretend it is and the alternative is so terrible - then folks across the nation can see it for themselves, with their own eyes.
"Why don't I have healthcare like Massachusetts?" Then the tide turns, people see what works and support it. Progress is made and the country moves on to the next divisive issue.
Progress is found in diversity. The more choices our 315 million people face, the sooner they recognize good ones from the bad. It's quite sad that the most diverse country on the planet still can't recognize that and we all squabble over centralized power when the REAL solution is right in front of us.