Is there a way to upload multiple users from the CLI instead of having to use the GUI?.. I just want to know before I have to put man hours into writing a python script for the process.
Sorry - there is no such tool.
There are a few pointers in this thread for using the DUM command line tool: Bulk add / import / enroll users
There is a short shell script here: Csv Datei integrieren (text is in German though).