I've already got this working as a prototype. Here are the changes I had to make:

• Replace the two dependencies that don't publish pure Python wheels to PyPI: click-default-group and python-baseconv
• Get Datasette to work without threading - which it turns out is exclusively used for database connections
• Make the uvicorn dependency optional (only needed when Datasette runs in the CLI)

TODO:

• Switch to click-default-group-wheel
• Remove python-baseconv dependency #1734
• Work around uvicorn import error
• Datasette setting to disable threading (for Pyodide) #1735
• Automated test for Pyodide compatibility #1737

Goal is to be able to do the following directly in https://pyodide.org/en/stable/console.html

import micropip
await micropip.install("datasette")
from datasette.app import Datasette
ds = Datasette()
await ds.client.get("/.json")