Hi,
Do not have a G920 but i was able to configure my logitech G25 and G27 under dolphin controller setup by selecting Dinput/LogitechXX and setting constant rumble.
the result is that there a constant force.
It allows the steering wheel to be centered/recentered with a constant force, but there's no effect on the steering wheel in the event of an impact during the race.
I don't know whether to configure something else in dolphin or add an FFB plugin on top of it. While all perfectly works with F-Zero GX game.
As per what we can read on the net it looks like force feedback is not implemented yet for FzeroAX.
Maybe it is due to the Motor setup disable patch?
Hence you may expect your G920 to work fine but without any FFB for the moment.