I prefer to use an 8" tablet as it's easier to see than a phone for me. I happen to have an iPad
mini 4 which works very well with my
Mavic 2 zoom. Apparently you need a mini 5 for the
Mavic Air 2.
I prefer Android personally, but my experience has always been with cheaper Android devices that can only just do phone calls. No chance they would fly a drone! So whichever operating system you choose you need to invest in a decent one. I got the
mini 4 because a good refurbished one without GPS and cellular is very affordable.