Even disabling the GPS or “location services” in the iOS security tab will not hold an app back from guesstimating your location.

This was with an Android, but how else does it guesstimate your location? I assumed via IP

Much location detection uses WiFi mac addresses sucked up by stuff like street view cars. Uses much less power. Google have an API to look up a set (min 4) of mac addresses and tell you where you are.

I built a tracker with an esp and two AA batteries. Worked like a dream.

That's using WiFi access points, not devices like phones.

Superman is always on the lookout for Kryptonite so he can stay away as far as possible :)