The feature you are referring to, the Jetway batter charger, relied on the fact that, at least with airplanes using a standard electrical system, it was possible to write the standard variable of the battery voltage, to recharge, simulating an external GPU.
The same variable is not writable with MSFS, so we cannot add the feature. Also, MSFS has a feature that has probably be added to make it easier to use that, at least on default airplanes or planes that use the standard electrical system, when you are parked on a gate, External power is always available no matter what, making the feature less useful.
