Hi there!
There are already so many requests and posts about adding custom georeferenced charts in SD.
It would be great to have the option to add our own charts — maybe we’ll see this feature someday.

But for now, it would be a really nice feature if the "Aerial Photography" layer were also available in flight mode, not just in planning mode.

Is there any chance we might see such a feature?

You're right, it only appears when you're on the ground, and not while you're in flight. We'd certainly look at revisiting that criterion if people want to use it for more scenarios than we originally envisaged.