HK isn't a sovereign nation, Taiwan is. Also, having the US go in would be questionable. Wasn't the "one country, two systems" treaty an agreement between uk and china?
I mean, you can make the same argument with "the earth is flat... depends on who you ask". At least when it comes to the Taiwan (the island) I don't think there's any doubt that the ROC government has a monopoly on violence there. They also have their own military, police force, and collect their own taxes, independent of the PRC.
Best I can recall, it was formed by Nationalists, partly Nazy government that had to flee after like a third Communist uprising when they relised there were more revolting peasants than they had bullets.
Obvious a lot of time has passed, but it's not quite flat earth. It just requires a sence of 'historical justice', however unhelpfull
It's a little bit more complicated than "ask Taiwanese", depends on whether you ask the indigenous people or those coming from mainland ~1949 and their descendants, you may get different answers.
I don't think you mean Native Taiwanese (as in Native Americans) here, so I have to say people are not unanimous about whether "Taiwan" is a sovereign nation.
Depends on who you ask.