From what I gather, the Chinese are behind, but a lot of their research amounts to scrappy, clever discoveries in how to use more novel technologies (for Qwen and Deepseek, its mixture of expert models, that can do inference using a portion of the model at a time). The chinese also distill information from American models, so there’s that.

The American companies, from my impression don’t involve themselves with such lowly “hacks” because they have so much money to just push forward with doing everything on big heavy models that run on the most cutting edge nvidia chips that they can, the moment, kinda sorta get on demand (I say that in some degree of jest).

The American companies would love to develop these 'hacks' because it would make them more money, something they are in existential need of right now.

They don't develop them because they don't collaborate publicly anymore.

Where would the whole industry be if Google never allowed publishing the transformers paper?

It's not a coincidence that the American AI industry grew fastest in capability when it was the most open.