serious answer
@eniko Annoyingly, the answer there is *sort of* yes. WebGL 1 and 2 could conceivably be deduplicated, given enough time and GPU driver updates, but WebGPU is built on Vulkan instead of OpenGL and is AFAIK simply not possible to support on older GPUs.
All of those require hardware acceleration to be usable; for those cases where that is not available, there's Canvas and SVG which have almost no overlap in functionality; one is a raster graphics API, and the other is a vector API.
Could these APIs conceivably be merged? Yes, but the total API surface wouldn't look much different from what the combined API surface is right now, so in terms of implementation complexity it wouldn't really matter.
Assuming that breaking backwards compatibility is acceptable, there are definitely a lot of things in the various browser APIs that could realistically be replaced or merged with a design iteration (think fetch vs. XMLHttpRequest), but I suspect that graphics APIs will not be one of those...
serious answer
@joepie91 @eniko There's a subset of WebGPU that works with OpenGL ES 3 (at least with the dawn engine). Once I migrate to WebGPU I will see if I can just delete all my GLES code without loss in compatibility/performance.