I've seen outfits like that at most auto parts stores (Auto-Zone, Checker, Pep-Boys). I briefly had one I got on sale from Sharper Image, but in order to calibrate the compass you had to drive the car in a circle several times and I wasn't eager to do that in a 40' motorhome. Plus there was something wrong with it, don't remember what.
It literally is what you called it, a compass with thermometer(s) and optionally other clock like functions built in. It works on magnetic fields, not reception from satelites.
I also have that very thing built into the mirror on my GMC pickup; works pretty good.
John (40' 2004 Country Coach Inspire DP)