But isn't it easier to copy some existing approach than to create it from a green field? ASML tech is presumably highly protected, but China is also very good in spying, hacking etc.

This stuff is really hard to copy. China basically had to put in all the cold era materials research along with getting up to speed on current tech, from scratch. They were/are always going to catch up because they have the resources to, but there are no shortcuts.

Yes. But it's not as simple as just having access to ASML's ip. They have exclusive rights to all the components and inputs, which are also protected and are also hard to make.

It's a whole system that China needs to duplicate.