[almostgotcaught]

> The amount of effort required to design and implement such a device makes it difficult for a single company to invest in, but many interested users of it could band together to create a viable open source implementation.

There are lots of companies that have their own high-performance accelerator cores (though not general purpose). Multiple generations. Eg every FAANG (except Netflix, that I know of).

There are exactly zero such OSS cores.

So I think you have this exactly backwards.