mapbox/mapbox-gl-js ? reverse-engineered prompt

I want to build a JavaScript library for showing really nice, interactive maps on the web. It should be super customizable, so I can change all the colors and styles to match my brand. People using the map should be able to pan, zoom, and even tilt it to get a 3D view.

I want to be able to add my own data on top. For instance, I should be able to add custom icons for points of interest, and when someone clicks one, a little pop-up bubble appears with more information. It would be great if it could also handle more complex data visuals, like grouping tons of points into clusters, or even showing data as 3D bars on the map. I've also seen maps with 3D terrain and hills, which looks amazing—let's add that. The library should use WebGL to make it fast and smooth. I assume this will need a Mapbox API key to work, so make sure there's a way to configure that.