I wouldn't be so sure. Last time I went in Taiwan, a friend of mine told me surprising political stuff like: "this part of town is KMT, that part is DPP", "if neighbours learn my family don't vote KMT we're in trouble" and "my grand-father is from the continent, that's why I have these facial features. So people knows I have mainland ancestors and thinks I'm KMT".

Of course it is just a data point, but that's may reveal underlying things that totally foreign for European/West way of thinking politics.

That is not true at all. There is still a lot of animosity between the two factions, even if some intermarriage has occurred (and is irrelevant given that they are genetically identical anyways, as native doesn't refer to the real Polynesian natives). Mainland-native identity politics is very real.