If WebGPU really does perform better in an apples-to-apples comparison (i.e. running the same shader) then there's something seriously wrong with Apples WebGL implementation.
edit: here's that example translated verbatim to WebGL if you want to compare: https://www.shadertoy.com/view/Mt2fRy
Most of the WebGL demos that get posted around here, always have issues running on my mid-range devices, that don't have any issues playing my collection of 3D games.
So I still look forward to a 3D Web API that can actually compete with native 3D across all mobile devices, not only on flagship ones.
Or proper implementations of WebGL, if that is actually the issue.
https://news.ycombinator.com/item?id=16086537
I suspect that Three.js is the main reason why so many WebGL demos are slow, rather than WebGL itself.
Might be, but what counts is the perception when someone goes to a given web page.
EDIT: Just tried your shader toy example on an LG Power X, with a Mali T720, it averages on 20FPS.
So the exact equivalent in WebGL is noticeably harder on the system than the WebGPU version.