I think my question made it clear I'm not simply assuming China is somehow cheating here - either in the specs of their current product, or in stealing IP.

No, I just struggle to reconcile (but many answers here go some way to clarifying) Nvidia being the pinnacle of the R&D-driven tech industry - not according to me but to global investors - and China catching up seemingly easily.

Unfortunately I think global investors are quite dumb. For example all the market analysts were very positive about ASML, Nvidia, etc but they all assumed sales to China would continue according to projections that don't take US sanctions or Chinese competition into account. Every time a sanction landed or a Chinese competitor made major step forward, it was surprise pikachu, even though enthusiasts who follow news on this topic saw it coming years ago.