I do not have a stance on the Maldives, Guam, etc. as I lack enough historical and current context. What I always do is try to derive positions based on the human right to self-determination.

About Taiwan. I find the claim that since an absolute monarchy controlled the island 150 years ago, that then a government which was the result of two (is my count correct?) revolutions overthrowing that monarchy and then another government, a government which failed to conquer the land by military means by 1950, and now after people have lived independently for over 75 years (over 25 of which as a democracy) that said government has any right to dictate how said people should live to be simply absurd. If the people of the RoC wants to join with the PRC, that is for them to decide through their own decision processes. Historical claims like this may make sense for unpopulated tracts of land, but here we are talking about the rights to self-determination of more than twenty million people of which the vast majority were born well after 1950. This would set a terrible precedence and, frankly, it feels akin to how emperors and kings of old asserted their "rights" and not how we move towards a more just world.

Also, Hong Kong? If anything, Hong Kong shows that the PRC is a poor custodian for a pluralistic country with multiple parallel systems. I once thought it reasonable for Hong Kong to be "returned" after the historical travesty that were the Opium Wars, but I have heard enough first-hand accounts of the suffering and tragedy that unfolded over the last ten years to reconsider whether I prioritise history over the people that are alive here and now. It was not that Mao and Xi "unfortunately had to use force" against Tibet and Hong Kong. These were calculated choices on their part and history shall judge them the same way we judge any other oppressor for their moral failures.