The problem with satellites is that their tracks are predictable. You know when to hide things. One technician who worked for me was in the Air Force, and there were things that they had to put away due to when a certain satellite would fly over. As for drones hovering, it had better have a small RCS. Nice thing about the Blackbird/Oxcart/alleged successor is that it gives little notice and has limited exposure time. The Blackbird also had a low RCS.
We have satellites that don’t have fixed orbits. But there is that minor problem there.
Drones have a very tiny RCS, cause they’re tiny.