Yes, this also has the advantage of speed perhaps. I can see, deleting specific apps (and their data) as thing #1, and thing #2 would be certain directories. Of course, the problem is, are icons going to be vanishing off the home screen, when the agent is looking at it? Or will the unlock -> screen coming on, be super slow?
Of course the problem there is, many people have an app store installed, and app stores have histories. And logs. And "what you used to have installed" is so easily found under Google Play, for example.
As someone else said in this thread, the law isn't code. It's not if-then statement based. It's also predicated upon intent in many cases. What actions did a person take, and why, when told to (for example) unlock their phone.
The problem here is that if you are asked to unlock your phone, any action you take to thwart that request by "trickery" to get data deleted, could be construed as 'deleting evidence'. So while some methods might make it more difficult for the border agent to realise "something happened", if they're suspicious still, then you're still in hot water.
In the eyes of the law, the court, and likely the jury, you've done a sneaky thing to thwart evidence collection.
The only safe method is a full wipe prior to travel. In this manner, you're not deleting evidence when told to hand it over. It's an entirely different bar. They can be cruel about it, and take your phone for a few months, but you're not going to be in legal hot water.
In as no one will see the phone is wiped until you are compelled to unlock it, there's no greater change of the phone being seized. You're already being investigated. Just be blunt, say "Whenever I travel, I just wipe it", and that's that.
This is why it's a shame that GrapheneOS has no viable backup solution. Its build in method is unreliable, and doesn't work very well, and is gitchy, it's a very well known problem.
And Android and ADB sometimes have issues with large backups of directories, and so you have to manage that with tar + stream and other business, but at least working around that is easy.
But if you could backup individual apps and all their data, you could uninstall all your privacy laden stuff, cross the border, and reinstall in minutes.
That's the true, legal way to travel safely. Especially if the app removal resulted in a 'shred' of the data files instead of delete.
If anyone has ever struggled with large data backup/restore, here's the only real method I've found for copying large swaths of files from/to via adb:
adb exec-out 'tar --dereference --create /storage/emulated/0/dir/ 2>/sdcard/backup-errors.txt' |dd of=/tmp/backup-$(date +%Y%m%d).tar && adb shell cat /sdcard/backup-errors.txt
and to restore
dd if=backup-20250309.tar | \
adb exec-in 'cd /storage/emulated/0/tempdir; tar xpvf - 2>/sdcard/restore-errors.txt' && \
adb shell cat /sdcard/restore-errors.txt
Or something similar.