How much esoteric hardware will bluetooth let me talk to? Can I talk my best friend's telescope? What about my coworkers oscilloscope? What about the kiln in o

How much esoteric hardware will bluetooth let me talk to? Can I talk my best friend's telescope? What about my coworkers oscilloscope? What about the kiln in our chem lab, or the cash register at the deli I bought lunch at? Old CANBUS ports? What does bluetooth talk to? Headphones, fitness trackers, car stereos... and aside from a few random appliances, not much else. Yeah maybe in twenty years when everything and their mother was made with bluetooth support, but that is a LONG ways away