> As you mention, the article you link says that the majority of HKers want to be a part of China. That's where I'm getting that from.
There's certainly a contradiction there. I'd attribute HK public opinion against independence as recognition that they're geopolitically unable to exist as an independent country, and a desire for the perceived next best thing (which they really did have until recently), and not as any actual desire to be controlled by the PRC. How else do you explain public opposition to the national security law?
> I do believe China could do better in terms of securing individual liberty for their citizens, but if that comes at the cost of its sovereignty, then obviously some concessions have to be made.
And I'm not sure how Hong Kong's previous autonomy (or any other freedoms) would come at the cost of the PRC's sovereignty? If the CCP wanted to hold democratic elections tomorrow for all territory within their military control, then they could do it. Inertia being what it is, they'd probably even win! No outside force is preventing the PRC's government from responding to the will of the mainland's or HK's people; but instead, Beijing is transitioning from the pragmatic sort of technocracy that Deng Xiaoping introduced to plain dictatorship. The end of Hong Kong's autonomy is just another step down that path.
Finally, countries express opinions about the affairs of other countries all the time. The USA exists in part because of French meddling in a British colony. Everyone likes to do it, and no one likes it when others do it to them. As long as it's happening openly, I can't get too upset either way. America is certainly flawed in many important ways, but I can express those ways openly without fear for my personal safety, and that free expression has historically resulted in what I consider positive change. Something close to that used to be true in HK, and now it isn't. I suspect that became inevitable with the handover and with Xi's self-coronation, but I think it's a great loss.
ETA: And I'm not sure whether it's by coincidence, but your points closely track Beijing's usual talking points against the USA (sovereignty / "internal matter", incarceration rate, etc.). If you don't mind sharing, where did you develop these beliefs?