> the issue is that when a phone is unlocked, they can just plug in a USB device and scrape everything off it

That's useless if the backup account and the main account use different keys for the home partition.

VeraCrypt (used to?) have this. It was called a hidden volume. One volume, but two keys, two passwords, and two different containers full of data. Technically, the second volume is written into the partition "from the back" using key 2, while the first volume is written "from the front" using key 1.

Fun fact, there's no protection against writing over data in the other volume if volume 1 + volume 2 exceed the size of the partition - and there can't be, otherwise the volume wouldn't be hidden.

Yep, and there is also no way to tell if a hidden volume exists, because a volume without a hidden volume would fill that space with random data indistinguishable from a hidden volume.

For now the courts in the US have set a different barrier for automated extraction and hand searches. For now.

Why does the USB port need to even work anyways? It could just be designed to look like a USB port but fry whatever expensive and proprietary phone hacking device they bought from some scuzzy Israeli ‘security’ company when it’s plugged in.

It has to be a once-only effect tho. If it's repeatable, they've got you for some string of felonies.

I wonder what would happen if it was every time, but you never told them it was a USB port

Of course! It charges my personal taser (which I wisely left at home on this trip out of the country).

For using the phone.

Not possible unfortunately due to low level SSD architecture[1] and other reasons:

https://nitter.net/GrapheneOS/status/2082153517234676150#m

[1] https://veracrypt.io/en/Trim%20Operation.html

https://veracrypt.io/en/Wear-Leveling.html