All the optimizations mentioned except LTTB downsampling in compute shaders can be done in WebGL.

Web charts with > 1 M points and 60 FPS zooming/panning have been available since 2019. For example, here's a line chart with 100M points (100x more): https://lightningchart.com/lightningchart-js-demos/100M/

But still, love to see it. WebGPU will surely go forward slowly as these things naturally do, but practical experimentation is essential.