This is a suggestion for all devices (or at least all TWRP compatible devices).
Once TWRP is installed, why not suggest to the user to boot into TWRP > Backup > select every boxes and swipe to backup, then transfer the backup on a laptop or do nothing if the backup up has been made on a SDcard.
This way, even if the installation doesn’t work, the user can still restore the system (and data).
One case for which this would have been useful :