In the radio spectrum, American satellites are able to lock on to the oscillator in a digital watch from outer space. This is, however, only possible if the watch is not in a city, where there is a lot of interference. The watch would have to be worn by a survivalist way out in the back country. The NSA has spy satellites with dishes over 200 feet across, which are unfolded when the satellite reaches orbit. This is completely possible, because very thin mesh can be used in outer space, where no support structure is needed to keep the dish in the correct shape. Such satellites can lock on to any electronic device under the correct conditions.
As far as outside the NSA? All I can go on is press releases. And back in 1987 there was an article published by the St Paul Pioneer Press that had an image from an American spy satellite that clearly showed the headlines in a newspaper being read by a Russian on the sidewalk. So, that is quite perfect for the spy state.
Obviously this would also need good conditions, the atmosphere is an obstacle, but there is no doubt they can see you from space. I saw an unconfirmed picture from an “American spy satellite” in 2008 that had artistic photographic quality from outer space. It was zoomed in on an Arab from above, and the colors and detail it captured were surreal. It would have, at that time, taken a Canon 5D to bag such a beautiful shot from even 100 feet away. The perspective of the shot strongly indicated that it was not a 5D that took it.
You do not need “beautiful” to track and kill someone.
High quality gigapixel imagers have existed for almost a decade now. How good would such an imager do if it was only 300 miles up and looking through a 20,000X optical zoom? Such lenses are easy when the military pays for them and there are no structural barriers to long focal lengths in outer space.
The problem with photographic spy satellites is limited resources. One satellite cannot get a clear picture of a fisherman on lake superior at the same time it gets a clear picture of a cherry picker on the shores of Lake Michigan, they have to be planning ahead to get a shot and are still only effective for military purposes, such as getting the details on a military installation or the position of a ship. Tracking moving people who are pre set targets in real time is still practically impossible. That is what drones are for.