I just came across your post as I was trying to learn more about the M5Stack platform for my own diabetes-related project.

The radio used in LoRa module can be used to communicate directly with Medtronic pumps, so I'm working on using it for a full rig (closed-loop artificial pancreas), as well as a RileyLink alternative. It depends on exactly which radio pins are connected, so I don't know whether the M5Stack will work yet, but I'm hopeful.