What do we think Taiwan is?
Do we think that it is an island nation where all the Taiwanese live? That's not what the people on Taiwan think, nor what the Chinese think. Both agree that Taiwan is a part of China. They only dispute who is in charge of China including Taiwan.
Jimmy Carter, in a surprise unilateral move, made it official U.S. policy that the government located on the mainland of China are the true government of China. We don't recognize Taiwan as a separate nation either.
Maybe Nancy Pelosi thinks that we should recognize them, but I don't know if they'd accept being recognized as a separate nation from the mainland rather than the Chinese government in exile.
Anyway, Biden wants to kow-tow to the communist government on mainland China because they pay his family so much money. If Nancy Pelosi is sidling up to Taiwan, it is most likely for some financial gain of her own. Either that or pumping her ego by going against Biden. I see no benefit in her trip, but I don't see much downside either.