I'll start off saying that I haven't done significant testing of this, but I wanted to report it anyway.
My phone does not really work as a presence sensor, as the A+ seems to think it goes inactive while it is still in the house. My guess is that is because of Doze Mode on Android 6+.
I had created a rule to switch to home mode and turn lights on when the phone was detected, and switch to away and turn some lights off when not detected, but the latter would happen while I was at home (and the phone was definitely not dead).
The easiest change I could imagine would be customizing a timeout for the device to be considered inactive.