I too struggled to find the best way (my drone battery would die whilst I tried to trf gigs of vid through the cable to my iPad and I'd sweat over increasing battery temperatures).
I finally found this which works a treat!
OMARS® USB C Micro SD/TF Card Reader with USB 3.0 Male: Amazon.co.uk: Electronics
You remove your sd card from your drone, slot it in this stick, plug it into the iPad and use the simple inclusive software to move or copy files to the iPad (mine is
air2).
2 things to note:
1. After you paste the files to iPad, they seem to go into a temp folder so you simply select them again within the software and select move and paste them to 'iPad photos' then they appear in the gallery (it's self-intuitive so I won't post a boring walk through)
2. If you set up your drone to record both lo-res and hi-res files and want to copy both to your iPad, complete the 2 stages above on one set of files before copying/moving the other set because file names are the same and they would overwrite at stage 1 but iPad creates its own names at stage2.
Sorry I'm making an extremely simple process sound complicated but it's one of my life-skills
Huge files transferred in just a few minutes
I understand people using Mac/Win programs to edit but I try to keep away from my PC and was able to sit on the sunbed and burn nicely whilst editing on iPad with DJI Go4.
Only real app problem I find is the gamble of whether the rendering process will complete (it tends to crash out many times before being successful). You don't lose anything except time and body weight through sweat as it's taken 2 hours to create the project - but I digress..........