@arnaud Thank you!
multi-page apps
This may be included in Multiple scripts · Issue #4 · whitphx/stlite · GitHub (and maybe some additional adjustments specifically for mutli-page apps) 
Technically, the current version of stlite writes the Python script specified via mainScriptData option into the Emscripten File System so that the Streamlit server can read it as if it is a local file. So I plan to simply extend this mechanism to transmit multiple files 
You are correct.
pd.read_csv() does not work when an external URL is given because it tries to establish HTTP connection to the external server but it is not permitted in the Pyodide environment. See Roadmap — Version 0.24.1 for the details.
So pyodide.httpis the solution although I’m not sure if it works well in a Streamlit script, which I think does not support async code well. If so, this ticket might help in the future.
Or wait for Multiple scripts · Issue #4 · whitphx/stlite · GitHub as described above.
FYI,
https://pyodide.org/en/stable/usage/faq.html#how-can-i-load-external-files-in-pyodide
is also a related topic although this cannot be used within the current stlite API.