At this point, Taiwan’s only hope would be to form a mutual defense pact with South Korea and Japan.
Of course that would kick off Pacific WW-III....
Japan and S. Korea hate each other’s guts. (South Koreans would say with good reason given what Japan historically did to Korea.) Still potentially at war with each other over who owns the little island of Dokdo. Which is now occupied and heavily fortified by the Koreans.