"High-altitude winds between 1,640 and 3,281 feet (500 and 10,000 meters) above the ground are stronger and steadier than surface winds. These winds are abundant, widely available, and carbon-free.
"The physics of wind power makes this resource extremely valuable. “When wind speed doubles, the energy it carries increases eightfold, triple the speed, and you have 27 times the energy,” explained Gong Zeqi "
In all your examples there is the ground to provide a counteracting force. Maybe I am misunderstanding what you mean by untethered, but any initial airspeed difference between the wind and your system will eventually vanish and you’ll move along with the surrounding air.
I co-founded an AWE startup 8 years ago and let me tell you, literature does not support your claim.