wouldn't the current be the only thing that would change?
Well if the current changes (and I'm sure it does) and the voltage doesn't (because it's regulated) then the
resistance has to have changed, right? Not even G can get around Ohm's law you know......
FYI alloys like I think are being used have changes in resistance with temperature. Ideally they have "positive temperature coefficients" (often abbreviated 'PTC') so that as the heat goes up, the resistance also goes up to throttle the current back some to compensate. If you have a NTC it's unstable and can 'run away' or 'hunt' under constant drive as the thermal load changes.
This is why, for example, your bathroom heater doesn't blow up when the line voltage at your house varies a lot.
If this unit reads that out directly as a changing resistance it's not only fun to watch but might even give a clue to what the real temperature is inside the coil (if there's enough resolution of course). This is the way you measure the working temperature in electric motors for instance. Copper alloys used commonly in wire have a TC (actually called 'alpha', even before THC used the name for a vape....) of about .004 (positive). This means for every degree C temperature in the motor rises, we expect a .4% rise in resistance. If we measure the cold motor at say 10.00 Ohms and it goes up to say 11.00, a 1.00 or 10% rise we're looking at a 25 degree C rise. If it started at 20 C it's now 45 C inside the coils. We might be able to do the same with our carts????
OF