For me it' been covered above,
POI to be able to survey for example a tower or house.
Expo on all flying and camera controls to be able to smooth especially yaw control and gimbal tilt
In Manual control the h520 flies incredibly smooth but in Angle mode it is very jerky in all movements. Please smooth out Angle mode.
On waypoints the transition from one waypoint to the next could be classed in Some cases violent!
Histogram on camera,
More shutter settings
Custom white balance in Kelvin
Exposure bracketing
Sort out distorted lens in dng and video
Fix fuzzy and muddy jpg images
basic needed commercial camera features
To be able to move the gimbal, pan and tilt while on a waypoint mission.
Higher speed needed under certain circumstances
I don't use it but it might be useful is object avoidance actually worked
All the above.
And specifically a fixed shutter speed / exposure setting - obviously it can’t change aperture but can change iso..this is specifically for photogrammetry in lower light where a minimum shutter is essential for images without motion blur.