One feature that would be so very helpful and speed up the use of the Osmo, would be the facility to lock the exposure.
Most cameras I own that have an auto exposure function, also allow me to set the exposure automatically and then lock it at that point. It then allows me to be able to pan/tilt the camera without the exposure suddenly changing because there is mre sky or other bright feature in the shot. Even my iPhone allows me to lock the exposure...

Hi,
Actually, you can control the aperture in DJI GO App. Right under the Shutter/Record button on the left side of the App screen, you can set following parameters in your need.
A: Aperture priority or 'Aperture value' enables manual control of the aperture, and shutter speed is calculated by the camera for proper exposure (given an ISO sensitivity).
S: Shutter priority or 'Time value' enables manual control of the shutter speed, and aperture is calculated by the camera for proper exposure (given an ISO sensitivity).
M: Manual mode both shutter speed and aperture and independently set manually (with ISO sensitivity also set manually), where proper image exposure requires accurate manual adjustment.

Am I understanding your post correctly?

AE lock is on the Go app screen - top right, on the top info bar