I'll assume you've already taken to heart that the PRC invaded the PRV in 1979, as part of the Sink-Soviet split to punish Soviet allies in East Asia after Glasnost (this part of history is quite complicated, so it's OK that you got it wrong, we should all be learning all the time).

Taiwan, or the RoC if you prefer (since that's the name that some countries continue to recognise it as a nation under) , was indeed fascist (and certainly totalitarian) under Qiang Kai Shek, especially post retreat to Taiwan, (although not Imperial - the Imperial of China ended in 1911, and could only arguably be said to start again in 1959). However, with Lee Tung Hui's reforms and the end of dictatorship that changed, opening up the country, ending the death squads and brining about an opening up and freer press. And to preempt your criticism of the wave of 本生人 having been US educated, where would you expect them to have gone? The PRC? Or a nation trying to build ties with it? Japan and the PRC were pretty friendly at the time, so that would've been out too.

And since you notice that Vietnam, Philippines are indeed not a threat to the PRC, maybe you should reevaluate what I mean by: "Taiwan, Philippines, and Vietnam are about as much of a threat to the PRC as Palestine is to Israel." (with its iron dome, vastly superior firepower, and being on an entirely different scale of military capabilities, although to be fair to Vietnam, they did beat both the US and PRC in a war.)