I have some old 4 channel controller connected via (again, old) ATMega64-based USB "dongle" (really, it is embedded into controller case, so not exactly dongle). It shows at Windows as standard joystick (without any 3rd party drivers), but with unusual channel mapping (I don't know why): Throttle (left hand, vertical) is "X Axis", Yaw (left hand, horizontal) is "Rudder", Pitch (right hand, vertical) is "Y Axis" and Roll (right hand, horizontal) is "Throttle" according to windows standard "Game controller properties / Test".
I'm trying Demo and it doesn't see any channels but "Throttle" (left hand, vertical) which it maps to "Yaw" and show complete garbage, even draw circle out of big square (it can not be trimmed right). So, my controller is unusable :(
Basically it is dumb old full-analog FM controller, it doesn't have any mixers, channel maps or any other settings you could find in modern digital controllers.
Could it be used with FPV Freerider with some software channel remapping? I'm using it successfully with Aerofly Deluxe fixed wing / heli simulator.