Correction bro. Taiwan is not a country. It's a renegade province of China who latched onto the power of America to fool everyone into thinking that it is an actual country.
China is first world (well, not by the traditional alignment definition, but by the more common living standard definition), so that make Taiwan also part of a first world country, with all the associated advantages and troubles.
I think the point is that there will be huge whiplash effect going from normal first world life to suddenly being in combat. There is really no other time in modern history where a developed country fought with full strength around it's own territory.
Closest thing might be for Russia in Sudzha, but the amount of civilians in that city was so small. Or maybe the feeling of Israeli civilians after the IDF indiscriminately fired on car columns and hostages inside Israel during the immediate aftermath of the Hamas offensive last year.
Imho the "whiplash" effect will make it so that people who aren't strongly ideologically motivated will quickly flee. Mainland Chinese have an ideological reason to defend their homes (especially if US/Japan begins a full scale invasion), while I dont see why when it comes down to the wire, KMT separatists will actually want to fight. They'll get nearly all the devastation from the conflict but with no actual realistic paths to winning.
Plus in the event of the civil war restarting, even if US launches a full scale invasion of Taiwan, the daily life of people on the mainland will not change much. Meanwhile, people in KMT occupied areas would go from normal Chinese living standards to far below Gaza within a matter of weeks. I think this would have some profound psychological impact on them, possibly outright mentally breaking most of them.
People in Ukraine and Gaza are like frogs that have been put in gradually heating water, so they are able to fight coherently even during difficulty as they had a long time to slowly get used to difficulties ramping up. Whereas if you throw another frog directly into boiling water, something different will happen, although I'm not sure what.