When viewing observations with 'My Location', what is the actual range?

not sure which app you’re using, but in the Android app, if you choose to search by “my location” in the Explore screen, it’ll give you a map at zoom level 10 (on most phones, this would probably cover a large city and its surrounding area), centered on your coordinates. the area covered by the search will be whatever is in view on your particular screen when the search occurs. (you can sort of see this if you subsequently pan slightly, zoom out, or rotate your screen 90 degrees. you’ll see that the observations still reflect a particular rectangle that matches the original view port.)