I recommend not going with the integrated screen controllers, they aren't compatible with other aircraft or systems if you crash change or upgrade. I have an iPad 4 Mini with cellular that has worked excellently for the last 3 years. And with the iPad you have another mobile device for the plane or yourself to use when you aren't flying.
Full size iPad also works but it is way too big in my opinion.
If you go with the Mavic 2 Pro, the controller only holds a caseless phone between the bottom arms. This is the 3rd party iPad holder that I use:
https://www.amazon.com/Skyreat-Fold...ontroller/dp/B01N7RFDBA/ref=asc_df_B01N7RFDBA