Flying, TSA & my inreach

Never had them question it. I would just tell them it’s a GPS without getting into the whole satellite communication thing (unless they ask explicitly, of course). Be prepared to turn it on to demonstrate it’s not a hollow shell stuffed with something illicit. 

Treat it like a cell phone or laptop as far running through x-ray.

Flown with mine a 100 times. In fact, because it has a lithium battery it's supposed to be in your carry-on, and not in check-in baggage.