There are also surveillance blimps, which I believe would be closest to a real-time feed. Some can apparently stay up for 30 days at a time. These have been tested for domestic intelligence, and radar (rather than optical) systems have been deployed overseas.

https://www.washingtonpost.com/business/technology/blimplike...

https://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System