The backup file is simply a copy of your wallet file. It’s generally safer to backup with the command instead of copying because if you copy before the client properly shuts down, the copy you get can be corrupted. However with nu client there is a twist. There are two wallets, one for nubits called walletB.dat one for nushares called walletS.dat. By default you get walletB.dat backup’ed using the command, which is may not be what you wanted.
So the safest thing I think is restart your pi, don’t start nu, copy the walletS.dat (and walletB.dat if you want) to somewhere safe, then you can start the client to mint.
If you want to use your backup copy somewhere else, use the backup files to substitute the wallet*.dat on the new machine when the client is not running, then you are good to go. The password and motion info all go with the backup file.
