Hokkien and Min Nan are more or less the same language. If you really want to group it, then Hokkien is the mainstream form of Southern Min (Min Nan), not the other way round. https://en.wikipedia.org/wiki/Hokkien
97% of the people of Taiwan don't agree with you. And historically, Taiwan was part of China for four years (1945-49). And that only because of an invasion of a million-man army. In the 19th century, Taiwan was part of the Manchu empire, not the Chinese empire. Actually Taiwan was controlled by the Portuguese and Dutch before the Chinese arrived. Maybe it should be given back to the Dutch?