Yes, I think if literally every single person in Hong Kong had a gun that would be enough to stop the CCP. The entire active military of China is about 2 million people, less than a third of the approx. 7.5 million people in HK. Maybe the CCP could bomb the city into dust, but taking it over intact would be a practical impossiblity.
Maybe if everyone had guns and everyone was willing to let the city burn to the ground. But must people just want to get on with their lives for better or worse. The majority of Hong ong residents would not have supported all out war.
Sure, maybe it is possible if the residents are okay with the CCP taking over, but on the margin everyone being armed makes them taking action much more costly. Guerrillas were able win against the US in Vietnam, and Mao used guerrilla warfare himself and won against a better equiped military. https://en.wikipedia.org/wiki/On_Guerrilla_Warfare
