Maybe I'm dumb but what does WebGPU get you in reality that WebGL doesn't currently get you? I don't think we're going to see browser games any time soon (because it's trivial to just install a game and run it, and also the browser audio API sucks). And most visualizations on the web would be perfectly fine with plain old WebGL.
Basically, an improved API that targets a more modern graphics pipeline and has better support outside of browsers. You can write a graphics engine or custom renderer in Rust and have it ship across desktop and web. See Vello for example: