I think it would be helpful for the wasm/emscripten ecosystem to have an event loop as part of CPython. For example, recently we added Emscripten to the PyO3 CI PyO3/pyo3#2436. The asyncio tests have to be xfailed because there is no event loop. I would be willing to contribute one if there is interest.

The biggest drawback is that asyncio.run_until_complete and similar blocking APIs don't work, so it's different enough that many tests may not just work. On the other hand, I think that Pyodide's event loop has proven to be a very important feature.

@tiran @brettcannon