Hint user about passphrase strength when creating a persistent volume
The GUI bits should be stolen from existing, well-thought solutions to the same problem, e.g. GNOME Disks.
The (Modern Perl) code lives at https://git-tails.immerda.ch/persistence-setup/.
Feel free to ask details to intrigeri if you want to tackle this, or are lost in the code.
@sajolida wants to track this :)