> Can someone shed light on why China still couldn't copy the Nvidia GPUs in some form?

They have alternatives, like the Tian supercomputer was originally built with Xeon Phi chips that have been replaced with their own domestic alternatives.

A big limitation is getting access to fab slots. Nvidia and Apple are very aggressive about buying up capacity from TSMC, etc, and China's own domestic fabs are improving fast but still not a real match, particularly for volume.