I’m not willing to take a chance with my iPad yet.
I’ve been using my iPhone 7+ mounted in an adapter I 3D printed that clamps in the cell phone “jaws” on the controller. My phone is bigger than normal ‘cause it’s a plus and thicker since it’s in a OtterBox case.
I think this is where DJI wanted the “monitor” so that it would not block a direct path for the radio signal between the antennas and the drone.
I’m an Extra Class ham radio guy so I know that the radio control, video, and telemetry frequencies involve are microwave frequencies and so line-of-sight - almost like light. Stuff like the “monitor,” your body, leaves on trees, buildings, hills, etc. block the RF signals at these frequencies. The reason some don’t notice the blockage/weaker signal is because, although the signals are line of sight, the signals bouncing off stuff, all be it poorly.
I have a holder that would position an iPad I have above the controller but I haven’t used it yet. I’m sure the iPad, my body, etc. will block/weaken the RF signals when such stuff gets between the antennas and the drone. It’s just physics and a fact. The farther away the drone, the more pronounce the negative affects are likely to be.
You might be able to mitigate an iPad’s signal blocking by keeping the path between the antennas and the drone clear; i.e., don’t let the iPad, your body, etc. block the signal path.
Also, keep the controller antennas vertical, which will make them parallel to the Drone’s antennas. This will maximize the signal strength. Don’t have the controller antennas parallel to the ground or some other angle other than vertical. Finally, don’t point the ends of the antennas at the drone since there is an RF null or dead zone off the ends of the antennas. There is a similar null off the ends of the Drone’s antennas.
If you can avoid putting an iPad above the antennas, I would do so at least until you are comfortable flying the drone. Why add another thing that could affect its performance when you are still figuring out how it works?
Good luck.