You're describing the WebGPU spec and its different implementations.

OP claimed WGPU had native support for VK, DX and others. But as far as I know, WGPU just supports WebGPU being translated on the fly to those other backends, with the obvious performance hit. If I'm wrong, I'd be interested to know, as this would make WGPU a more interesting choice for many if, in reality, the code was native instead of translation.

Edit: https://docs.rs/wgpu/latest/wgpu/#backends it seems they indeed support native code in almost every backend?

I don't understand the question...

Those three WebGPU implementation libraries are compiled to native code (they are written in Rust or C/C++), and at least WGPU and Dawn are usable as native libraries outside the browser in regular native apps that want to use WebGPU as a cross-platform 3D API.

Yet still, those native libraries do a runtime translation of WebGPU API calls to DX/Vk/Metal API calls (and also a runtime translation of either WGSL or SPIRV to the respective 3D backend API shading languages) - in that sense, quite similar to what Proton does, just for a different 'frontend API'.