Decoy mode
Travel mode is useful when you can anticipate elevated risk and have time to prepare, but not if you get caught off guard. A decoy mode that can be quickly activated at any time, unnoticable to spying eyes, would on the other hand be supremely useful.
A typical implementation of such a decoy mode would be using a decoy password/passcode, which when entered appears to unlock the app but instead shows a selection of fake or less sensitive/valuable content.
Biometrics will likely be incompatible with such a feature, but I would gladly trade Face ID for decoy mode.
