Are you referring to the first nations coming over the Bearing land bridge? Because that's an extremely loose definition of colonialism and would mean literally the entire Earth has been colonized since the beginning of our species.

If you want to make the argument that everyone who isn't descended from native Americans leave North America, and everyone who is descended from Han Chinese leave Taiwan, make that argument.

Did I say that? Hmm, must have been in a parallel universe because I definitely don't remember saying that. There's a difference between saying that the land is stolen and that needs to be reconcilled and saying everyone of a certain race needing to leave. Decolonisation is rarely about making anyone leave, certainly not about making any ethnostates, it chiefly means giving sovereignty and representation to Indigenous governments, which, the KMT is not an Indigenous Taiwanese government and doesn't give sovereignty to Indigenous Taiwanese people, so how will Taiwan being a country (under KMT rule) be better for Indigenous Taiwanese people again?

(BTW, if someone says that every Han person needs to leave Taiwan or Tibet or whatever, by the same logic, it also means that every Uyghur needs to leave Xinjiang, because they migrated into the region when Chinese people already had a presence there. I love pointing that out to "go away, Han's!" people and then watching them lose their minds.)

BTW, most Americans are sympathetic to indigenous independence movements. Americans take great pride in their native American population and don't want to see them extinguished.

HAHAHAHAHAHA

Yeah, they're sympathetic riiiiight up until they're personally affected in any way by giving Indigenous people any sovereignty. Go watch Silver Spook or any of the other actual Indigenous people's political content and they invariably tell you about how utterly empty the support they get from the rest of the population really are. Shocker, learning about Indigenous people from white people won't get you an accurate picture of their situation! For more information by actual Indigenous people, visit https://therednation.org/

Actually, it might be worse than not supporting them at all, because you're apparently no longer allowed to point to colonialism as a source for any Indigenous issues anymore, because "well we like them now! if they're still suffering, it's their own fault!" As someone living in Canada, you'd be surprised how many people believe the previous statement unironically.