The controller is not a good design for mounting anything larger than a phone or 8 inch tablet.
I have used a Samsung 10.5 inch Tab S for my Mavic Pro.
Great size for seeing what the drone sees, but it's really heavy and wants to rotate the tablet and controller. I have a couple of mounts to use, and both do that.
I would think a smaller tablet would be much better in the long run. Maybe the Samsung 8 inch Tab A might be a better choice.
Must say that most of the time I use my Samsung S8 phone since I really have problems connecting to the drone with either one of these devices. The Tab S is so heavy it becomes frustrating trying MANY times to connect. So lately I just go with my phone.