I wonder if this mode would be helpful to protect myself if US border control forces me to unlock my phone so they can make a copy of all of my phone contents.
If you are a US Citizen or Permanent Resident, Border Patrol cannot prevent you from entering the United States. They can, however, detain you for up to 72 hours and confiscate the locked device if they have "reasonable suspicion". The confiscated property will be returned eventually.
If you are not a US citizen, refusal to unlock a phone and allow inspection, inclusive of allowing access to social media and corporate apps, will probably result in denied entry. They also have the right to detain you until indefinitely until you unlock the phone if they have "reasonable suspicion", but requires a court order within 72 hours.
Most foreign counties have similar rules in place for residents and non-residents.
They don't usually return the devices they steal, and most people travel with a total device value lower than the cost of an attorney and lawsuit to force the return.
The sterile area between the gate and the border control is treated as international waters/lands, which sounds fine, and IIUC there is the logic that laws don't apply there so you can be forced-forced anything free from constitutional protections. Not sure if that actually works though.
It would be a good idea to enable this before going though any border controls. Doubly so for countries that require apps to be installed before entry/upon entry/after entry.
ArriveCAN (Canada), Mobile Passport Control (USA), WeChat (China), and other mandatory government apps would be perfect vectors to stage highly targeted attacks.
