This makes me wonder what sort of semi-pro astrophotography might be possible using a disassembled small cinema camera (black magic pocket 6k, for instance, or a similar priced full frame mirrorless or DSLR) with a peltier cooler or refrigerant loop heatsink attached to its back side.

How close could one get in performance to a very costly astrophotography setup, for under $10k? Not counting the cost of the telescope/optics in front of it, just talking about the sensor part.