@john_t , I think DFS is tricky on drones because it requires a very good calibration (intrinsics, extrinsics) and the extrinsics cannot change, which is hard to guarantee on the drone. Alternatively, a robust system would be needed that will continuously recalibrate extrinsics over time. This may be the reason why stereo is not easily to use with consistent success on drones.
ToF works well indoors with range up to 4-6 meters, but outdoors the sunlight will severely degrade the performance. Some technical details are available here : https://docs.modalai.com/M0178/
Alex