Yes, starcams are standard equipment on satellites including Cubesats because they provide more precise attitude information than any other available sensor.

Yes, starcams are standard equipment on satellites including Cubesats because they provide more precise attitude information than any other available sensor. There are numerous free-software packages for star tracking; a quick search finds https://github.com/spel-uchile/Star_Tracker https://github.com/spel-uchile/Star_Tracker. I don't know if there's, like, an Android app that will do the required sensor fusion to tell you where on Earth you are.