Adding support for Orbit/Spiral within waypoint flights for older drone models requires special treatment as they use curved turns instead of smooth curves, plus they don’t use KMZ. At this time, we have not made this a priority versus other features. If we receive a lot of interest we will certainly bump the priority
The “Orbit” function in the Litchi app is separate/distinct from the “Waypoint” function. Older drones that use the traditional Litchi curves fly a path that does not go through the waypoints. Therefore, an orbit in older drones would not pass through the waypoints that are used to create it. Whether or not the Litchi developers choose to implement that is a separate question. There may also be other factors that I am not aware of.