Most of these "alternatives" focus on CUDA C++, and overlook what actually makes CUDA interesting.

Already in 2020,

https://developer.nvidia.com/blog/cuda-refresher-the-gpu-com...

There is also ZLUDA, which is open source and works on pre-compiled binaries.

https://github.com/vosen/ZLUDA

Its easier to just get rid of your legacy code entirely and use Vulkan for compute, or have your compiler emit SPIR-V directly.

No reason to tie yourself to Nvidia's moat.

I have been trying for cuda -> metal, to run it on mac, https://github.com/lulzx/cuda-metal

every CUDA alternative follows the same arc: bold launch, works for 3 operations, then a Discord server where the last message is 'any updates?' from 2024

There's nothing wrong to run CUDA on non-Nvidia hardware. CUDA has an interface that is reasonably well-designed, well-documented/reverse-engineered, and battle-tested for decades. What we need is not to invent another interface just under the name of 'open standard', but to implement the same interface. ROCm is exactly doing this, and so are other hardware SDKs such as MooreThread and Alibaba T-Head.