So you think Nvidia should support a product that Apple already has plans to EOL in the next os release?
This is how big business works. Nvidia doesn't need Apple and is doing just fine without them. Why should they release drivers or try to support the only aging hardware Apple has left when there's no future in it?
Apple doesn't officially support eGPU and doesn't have a PCI slot in their new hardware. There's not one single product Apple makes that Nvidia can market their products around.
It sounds like way more work than necessary to support a beta on ancient hardware for very little in return.