No remotely western company will risk US sanctions violations or whatever other regulatory burden by using US technology where it can't be used. Even Chinese companies depending on how state backed they are might not be willing to risk it.
One is the mirror image of the other and neither economy can exist in its current state in isolation.
So China has the US over a barrel when it comes to actually building stuff, rare earths and all of that, but equally US sanctions still have real bite (a lot more than China would like) because China does have to do a huge amount of international trade to export and externalise its surpluses.
They're stuck in this unhappy marriage
Who says they’re stuck or unhappy?
This is politics. We’re all just bait. In reality they’re friends.
US and China have made more gains by pretending to be enemies than friends and they likely plotted it all together.