?

1. Create backup on device 1
2. Copy/move backup to microSD/computer/'cloud'
3. Copy/move backup from microSD/computer/'cloud' to device 2
4. ???
5. Profit!

Do you want to be able to share it straight from device 1 to device 2? Locally? With Bluetooth? That seems like something almost no one would ever use - unless I'm mistaken and there are many people who carry around two identical devices and move backups from one to the other for whatever reason. I have a feeling I'm not.

Edit: ah, just realised the backup only gets compressed when you move it to the microSD card, otherwise it's just the .vault directory. In any case I don't think copying a directory is particularly complicated, my parents can do it.