A few things:

#1. The download and restore backup method would work- except it doesn't capture what people would need. Exmaple: I have some thermal cameras that rely on old 32 bit apps that do not run on anything android 12 onwards- If i wipe those old phones, and restore- the apps often wanted to reach out to a server for initial activation- they would fail upon reinstall and i'd be out of the apps that are required to control my cameras and related equipment,which is worth thousands and thousands and thousands. And it'd be all dead weight and rendered useless.

(and competitors today do not compete- for example try finding a 640*480 30 hz or better form factor thermal camera that attaches to phones - they dont exist anymore)

\The solution is imaging- but there isnt a way to fully image phones and restore backups today. There used to be it seems- but not really with the latest.

Veracrypt- The weakness of truecrypt and veracrypt, the hidden OS option only worked if you converted your computer to MBR, which means you can't have a hard drive too large. Making a UEFI hidden OS has not been done yet.

I am aware of Shufflecake attempting to make a solution.

And the Hidden Volume option- isn't 'as' useful, and of course, your OS might make a copy and put it somewhere, you have to be careful. Any time I open a file, using the software tool Everything to search and confirm this- you can easily see Windows makes copies and temp files and whatnot in randomly named locations- that's the sort of behavior that would screw people over

We need fully image-backup capable Phones. I mean fully. Not just backing up some apps- as this refuses to backup apps you have that are no longer on app stores, or that Play Protect doesn't like, etc.

Next- Plausible deniability is a way forward- but you need multiple profiles, that are cryptographically indistinguishable, along with the phone being hardened so GreyKey /Cellebrite won't be able to exploit a way in. This needs to be built this way from the ground up ideally, eventually.

There has been research about making devices that treat all block space the same way so you can't tell if someone has 1, or 50 profiles or partitions, etc- and even stuff that overlaps. But nothing has come out - and especially, for phones.

After all, if you travel to a hostile country, you can tell them you have just one profile, and if they ask, you could theoretically mention a 2nd, and then show it- but you might have 3 more - and they'd all be immune to forensic inspection if the system is built right.(Yes, there's often issues you have to be careful of ,like setting this up so you dont destroy data when in other profiles,)

This is how you solve this problem -make computing devices impossible to analyze