Apples and Oranges. Unlike Ukraine Taiwan never declared independence. Ukraine's independence is internationally recognized. US, Taiwan's and PRC's official position is that Taiwan and PRC are the same country.
Yea, but Taiwan’s China and the PRC’s China are different. There was essentially a schism is the ‘40s with each side claiming to be the true government of China.
It's a literal fact and offical position of 99% of world's countries, including USA, PRC and even ROC that there is no such country as Taiwan separate from the mainland and that there is one entity called China of which the island and the continental areas are both part of. The only argument ever was who is the legitimate government of that China.
The entity that eventually became the United States of America first "established itself as the official colonial liaison to Great Britain." So that it could later conduct "diplomacy on behalf of the new United States."