The first practical usage of WebGL in the wild I can think of would be Google Maps, although it's easy to forget about the switch from the old server-side tiles to the vector WebGL thingy ( https://www.youtube.com/watch?v=X3EO_zehMkM ).

The still strikes me as one of the very few useful usages of WebGL that exists even today. There's other usages of course, like figma, sketchup, etc... But those rarely (if ever) benefit from the web's primary advantages of ephemeral & linkability, and would work perfectly fine as just classic desktop apps. Kinda like an awful lot of tools in those spaces still are.

Majority usage of webgl still seems to otherwise be ads & shopping. It seems likely that webgpu is going to be much of the same, although it has a chance of graduating out of the web platform as a potentially useful middleware abstraction for native apps that want to use the GPU.