Actually an app like what I'm asking for is pretty much the same thing many others might eventually be looking for. Something like what I'm asking for can be used by walkers/hikers, friends, even people in two separate cars.

Just doing a simple search for "real time gps tracking" got me gobbs of hits. I found a little article on someone's search, Best free GPS tracking apps for Android Looks like they recommend Life 360 too. I kinda like the second one on their list, Real-Time GPS Tracker. What would really matter is being able to tone down the battery use so as not to drain things dry.