If you are involved in causes frowned upon by the government of the country you are about to enter, you may want to wipe your phone on the plane.

It's more difficult for three letter agencies if you fill the memory with random stuff and encrypt before wiping.

If you don't want your phone used in impersonation while out of your hands, adb shell can be used to take out IMEI, BT and WiFi.

Simpler to just swap mainboards - available on Alixxxx