The map shows why China wants Taiwan and why nations in the area don’t want (mainland) China on Taiwan.
China does not have free access to the Pacific ocean! In case of war any naval vessel is in danger from land base aircraft. Having their ships based in Taiwan would open the Pacific to their navy.
China’s main problem is that it is not a friendly neighbor. In other words China does not have any allies. In case of war every nation in the area would be against China. They would not have to get involved in a land war they would just have to block any shipping in or out of China.
Since the 1970s China has been at war with the world using western money and technology to become a “superpower”. But China is a paper dragon and if cut off from western money it would collapse under the weight of it’s corrupt government.
At least that is my view of thing.