Wait do you not know what the KMT did? They're a rightwing party that killed/disappeared 30k journalists and intellectuals in Taiwan. How in the world is that comparable to the "union"? (But also yes Puerto Rico might be a better example).
In the sense that they're on the V-Dem index, they have election laws, they have voter rolls, they have voter turnout, etc. Yes they have one party, so you don't directly vote for the President, but neither do Americans.
It's democratic because it's on the index? Every state is on the index. China ranks 177 out of 179 states on the index lol. So sure, where a perfect democracy score is 1.0, they score 0.015. It's not zero.
Yes, the KMT dictatorship era was awful. You might be surprised to know that in Taiwan there are national holidays commemorating those persecuted by the KMT. The reason The ROC (Taiwan) is more aptly comparable to the Union when making an analogy to alternative American history is because it was the original, legitimate government of China and the PRC were the rebels, just like the USA and Confederacy.
You are confused. Look at Taiwan's present, not its long gone past. As I mentioned in another thread, during my last trip to Taiwan, I revisited the Chiang Kai-shek Memorial Hall, which features a museum where Chiang Kai-shek's life and rule are documented. The errors and brutality of his rule in particular are well-documented and preserved, officially accessible to all citizens and visitors. This is a wonderful example of transparency. You won't find anything like this in mainland China.
In the sense that they're on the V-Dem index, they have election laws, they have voter rolls, they have voter turnout, etc. Yes they have one party, so you don't directly vote for the President, but neither do Americans.