I would like everyone to know that if you have a brand new Kia, the process is even easier. I spent $20 on the Kia service manual access (didn't even know that was a thing until I read OP's post) it finally figured it out.

Modern Kias with the CCNC cockpit have a data connectivity unit that exclusively handles cellular. If you can get this unit unplugged, which only requires two Phillips head screws to remove, your set. It took me nearly 2 years to figure this out. Thanks OP

Any clues on how to disable any telemetry on a Kia Stinger?