There are several python to java compilers on the python wiki, but none of them work with pygame
https://wiki.python.org/moin/WebBrowserProgramming
For pygame, the only alternative is pygbag.
You don't really need to think too much about async, in the pygbag documentation itself they give you a minimal example of how to use it.
Simply put your game's main loop inside the main function that you call with async and there's not much more to complicate things.
Github has nothing to do with compiling your code, so there's nothing you can do there, unless the JAM asks you to share the source code.
Pyinstaller or Nuitka are useful for creating binary executables, but neither of those options are useful for the web.