Open source does that for you.

You can't sanction public knowledge. The mere idea of such should be ridiculed.

But open source still requires a license. And the company owning the license might be based in the USA.

Is it possible the USA government can say that this is open source and free for all to use, except for people in China.

For example, if Red Hat Fedora is open sourced, but Red Hat is a USA company. Then they will still be under USA jurisdiction.

Given all the lies and bullshit coming out of the current administration, I can actually see them doing this.

First, the RISC-V Consortium is an organization (now) based in Switzerland. Second, there is literally nothing anyone can do to stop you from making a RISC-V core, short of calling it "RISC-V". For that, you have to pass a few tests, but all trivial stuff for a serious contender.

On a related note, I don't think it's an accident that Apple almost completely avoids talking about "Arm" but instead calls it "Apple Silicon".

I think the difference is that China would just ignore it and still have all the access to the technology since it's open source already.

Not that the US gov't hasn't tried on multiple occasions...