I don't see this working for Google though, since they make their own custom hardware in the form of the TPUs. Unless those designs include components that are also susceptible?

That was why OpenAI went after the wafers, not the finished products. By buying up the supply of the raw materials they bottleneck everybody, even unrelated fields. It's the kind of move that requires a true asshole to pull off, knowing it will give your company an advantage but screw up life for literally billions of people at the same time.

TPUs use HBM, which are impacted.

Even their TPU based systems need RAM.

Still susceptible, TPUs need DRAM dies just as much as anything else that needs to process data. I think they use some form of HBM, so they basically have to compete alongside the DDR supply chain.