While the geofence idea is cool, I think it fails to be sufficiently reliable in practice. I mean not just the Stringify implementation, but everyone else too. Either it wastes battery power and resources on your phone, or it doesn't update often enough, or it's not reliable, or it's not accurate enough, or the logistics don't work with more than one person, or you don't always take the phone with Stringify on it when you go out.
I have two alternative solutions that I'm using instead:
I have a Google Home Mini near the door, and I just yell "Hey Google, leaving home" as I'm leaving. If someone else is home, I don't.
I have a Nest Protect smoke/CO alarm with motion sensor in the central hallway, and it automatically updates the Nest Home/Away status. It has a long period, at least a couple of hours with no motion to toggle to Away, and it has some smarts about the time of day and typical activity patterns in the house. It's generally a good fallback trigger if nobody remembered to use method 1 and we're all away for more than a couple of hours.