I see a benefit to what OP wants to do as I have wished my
Mavic 2 Pro could set the emergency return to home to the controller’s updated positions instead of the in situ one while filming a driving or boating scene where the passenger is in the vehicle being filmed controlling the drone.
Being that it can only either be set to return to home or return to the controllers position when the takeoff occurred is not convenient if you have already driven a couple miles away from the takeoff point with the drone following you and it decides that there’s not enough power to go back to home. Having it land or hover near the controller would be better. We tried filming driving through the desert once with my buddy passenger in controls as he filmed the car and he started fighting with the drone because it wanted to leave as we had arrived to the point of a safe flight return for the drone to fly back to it’s “home” point. we thought having it “set to controller” meant it would follow, but didn’t know that’s not how it works. It was pretty funny after we figured out what was happening.
Having this feature would also allow one to safely fly a drone that was following a boat, instead of it going back and landing in the ocean somewhere.
OP- if you ever figure this out for a Mavic, I’ll buy it.