My previous RV had that, and my understanding is that the “brains” are located in the main unit. At one time I happened across a link where somebody had pulled out all of that and replaced it with relays and a conventional thermostat - can’t find that now, but it was several years old.
Fortunately my new RV has Coleman-Mach units that have (seem to at least) conventional t-stat wiring so I’m hoping my thermostat choices will be more open, although I’m sure they’re 12volt powered so I’ll need to find ones that are battery powered or get a 12-24v buck boost converter to power them.
Terry