Official comment
Flying with RTK and the DJI ground station will put the RTK corrected GPS coordinates in your tags which will give you the most accurate results possible.
The DJI SDK remote is needed if you are planning on using any 3rd party apps like Map Pilot Pro.
https://dronesmadeeasy.com/phantom-4-sdk-remote-controller/
The problem with the RTK is you have to use their app to fly if you want to do the PPK correction workflow since the obs files only get saved on the DJI remote with the integrated display. The files are not recorded on the SDK remote.
So basically you can fly using Map Pilot Pro if you have the DJI ground station and the SDK remote but if you are trying to do PPK you have to use the stock remote.