Hyperfocal would be somewhere around 75-100 meters. Just tap anything at a distance it would be difficult to see the Mavic itself, and you're good.
When taking pictures of a landscape at 300 feet, everything in the camera's field of view is effectively at infinity as far as the focus is concerned, so I'm not even sure what the point is of having an adjustable focus camera on a drone. Seems like a fixed focus camera set for infinity would be perfectly fine for virtually all pictures and videos taken from a drone.