But to what degree might this 'meta-API' be different than WebGPU/JS? Might this effort effectively end up creating two, new APIs, each with different vocabularies (one for JS, another for C or C++)?
The whole point of Vulkan/Metal/DX12 is that since GPUs have their own MMUs it's totally OK to seg fault your own process from the GPU side. You just crash your process, but you don't take down the system.
That line of thinking doesn't really translate well to a JS API.