Further to msinger's response, the Mavic Pro controller uses Occusync v1 in the 2.4 GHz band, the Mavic 2s use Occusync V2 with both the 2.5Ghz and 5.8Ghz bands.
M2 Controllers ar not compatible with M1. But you can use the M2 Controler as Slave Controller (Dual Mode / Coach Mode) for the M2 simultanosly with the SC...And you must wait for the DJI GO 4 v.4.3.16 !!