As someone who has actually worked on this stuff soup to nuts, it's not as easy as people imagine, because you can't just support some subset of available ops and call it a day. If you want to make OpenCL pie from scratch, you must first make the universe, and support every single stupid thing (among thousands) and even mimic some of the bugs so that models work "the same".
This is hard and time consuming, and this field is hard enough as it is. What makes it even harder is that only NVIDIA has decent, mature tooling. There is some work on ROCM though, so AMD is not _totally_ dead in the water. I'd say they're about 90% dead in the water.
