Part of the reason for forking from SerenityOS was to allow adopting third party libraries. They've already added Skia and FFmpeg and a bunch of other stuff. WebGL will almost certainly be supported by ANGLE, WebGPU by Dawn or wgpu, WebRTC by the WebRTC library. WASM on the other hand is usually tied to the JS engine which is custom. I believe it's already partially implemented.
WebGL, WebGL2, WebGPU, WebNN, WebXR, WebAudio, WebRTC, WebAssembly? Etc....?
Each of those seem like a multi-year project for a team on their own if you're not going to take code from any other browser