And they propose to do this… how?

Chip lithography is the most advanced, complex, and finicky mass-production process that exists in the modern world, and Taiwan took decades to get there. Not to mention, Taiwan doesn’t have the industry that creates the machines that are used in the manufacturing process - that’s primarily owned by a handful of highly specialized European companies.

Even if the PRC were to execute the greatest industrial espionage campaign of all time and magically obtained all of the required documentation and instructions on how to do it, bootstrapping their industry to bleeding-edge standards would take years - likely close to a decade, if were being realistic - and the bleeding edge would have correspondingly moved on by then.

China is a country that couldn’t reliably manufacture ball-point pens (a deceptively nuanced product to manufacture, as a matter of fact) until a decade or two ago. I do not see them catching up with Taiwan, South Korea, Japan, the US, or various European countries in the near future, considering their semi-hostile stance towards the west. I definitely do not see them catching up ever if the PRC decides to send it and try to annex Taiwan, because that will seriously piss off the rest of the world. If you think the Russian sanctions are severe, consider what the sanctions would be on China for attacking a country that literally enables a significant fraction of modern technology to exist at scale.