conda-forge builds for ARM64 now ("miniforge"). Maybe someday conda-forge will build packages for WASM, too.
The pyiodide work would probably translate well.
There's a version of JupyterLab compiled to WASM w/ all of pyiodide called 'Jyve' that runs totally in the browser... Latest Chrome supports the new Native File System API "that lets websites gain write access to the native file system"
Jyve has a Brython Jupyter kernel; marked as unsafe due to there being no good way to sandbox the app JS from the notebook JS, AFAIU.
WASM and MAC labels is still an open security-related question, AFAIU.
PyQuery has a chained API that's familiar to jQuery users.
The DOM API in Brython could probably be easily ported to CPython (and then Jython, IronPython, PyPy, RustPython).
RustPython may already easily compile to WASM without any patches?