I really really like this, but 4 MB zipped is a bit of a hard sell :/ I've had a need to deploy small ad-hoc HTML tools at work, though, and my Python is much better than my JS, so maybe it's worth it.
Local intranet / work tools would actually be a good use case for this as the load is small (tens, hundreds, maybe thousands of employees at absolute most) and mostly the same repeat users so browser caching would make it snappy for them on future visits.
A public marketing page where it's the random internet of totally new/anonymous users who want to instantly find out info about your product would be the worst use case for this IMHO.
For one of the examples, I saw it coming down with pyscript.js - 1.1 MB, pyodide.asm data + wasm of 16 MB, and each python package as a separate wheel download (cool!), matplotlib of 6MB :)
A public marketing page where it's the random internet of totally new/anonymous users who want to instantly find out info about your product would be the worst use case for this IMHO.