This is quite interesting, Michael Kennedy, Brett Cannon, Nicholas Tollervey, and Fabio Pliger discuss PyScript running in the browser on MicroPython. MicroPython's WebAssembly is just 300k to download and loads in under 100ms. Here is the technical preview [1], here is the git repo [2].
[1] https://pyscript.net/tech-preview/micropython/
[2] https://github.com/pyscript/MicroPyScript