Neither of those cases have got anything to do with CCP wanting to export their governance model or invade foreign countries. This is apparent if you look at the historical context of the issues in those areas.
China isn't in Hong Kong because they're afraid of democracy. Under British rule, Hong Kong never had democracy in the first place. In 2014, CCP offered a limited form free elections for Hong Kong -- that's more democracy than under British Hong Kong. Why would they do that if they want to destroy democracy? The Hong Kong opposition shot down the proposal because they wanted more concessions. Unfortunate, because if it was accepted, it could have paved way for more democratization down the road.
As for Taiwan, the conflict exists because it's a leftover of the Chinese civil war. At the end of WW2, the Chinese Nationalist Party fled to Taiwan -- a part of the [People's Republic of China]'s predecessor, the [Republic of China]. Officially, both Taiwan and China claim to be the legitimate goverment of the whole of China -- this is the One China Principle. Heck, Taiwan' s modern-day flag is the exact same as that of the Republic of China.
Ever heard of Macau? It's democratic, part of China, and is doing fine under One Country Two Systems.
Whether anyone thinks Hong Kong and Taiwan should or should not be independent is besides the point, as well as totally irrelevant. The CCP has issues in those areas because they are, or used to be Chinese terrority. These issues are not new, and have been there since the founding of the People's Republic in 1949, back when the CCP was small and weak and in no position to invade anybody.
But these issues persist because many mainland Chinese people care. Unity is and has been a Chinese core value for thousands of years. The issues don't persist because the CCP is evil and want to destroy democracy. Even if Hong Kong and Taiwan were under a seperate communist rule, the CCP would still have issues with those areas.
The narrative that China is an expansionist invader is based on the twisting of half-truths, for the purpose of painting a "China threat" in order to justify spending more money on the military industrial complex. China has not fought a war or shot a bullet outside its borders for more than 30 years. In fact, if you take out the People's Republic's map, and compare ot to the maps of the last 2 predecessors (the Republic, and the Qing dynasty), you'll see that the People's Republic's map is smaller.