python3 -m pip install inputmodule from the python directory does not work. python3 -m pip install . works, but AFAICT it just installs the library with no entry point.
The binaries ledmatrixctl and ledmatrixgui do not exist. Unless I missed it, I think there is nothing in the repo that installs these.
After trying various ways to identify and launch an entrypoint and getting circular import and other errors, I finally stumbled on python -m inputmodule.cli to launch the GUI.