Taiwan's GDP/capita is 2.6x China's [1]. It grew faster, for longer, in large part through high technology.
Counterfactuals are always hard in history. But we literally have the nationalist government's democratic, capitalist successor kicking in way above its weight class economically and technologically. It's fair to say that if the '89 protest hadn't been massacred, the 21st century would currently be undoubtedly China's to rule. (I'd also put even odds on Taiwan having peacefully reunified by now.)
[1] https://countryeconomy.com/countries/compare/taiwan/china?sc...