Just to confirm, the official Lisk Nano wallet is an online wallet? As I cannot see a back up save file anywhere, so need to trust Lisk completely as they store the coins on the blockchain?
Will there come a safe desktop wallet with a back up option so that the user controls the coins on their own pc? A hardware (Legder and Trezor) integration would also be highgly wanted.
Your pass phrase is your back-up
It's like a Bitcoin private key.
All you need to backup is your pass phrase, your coins are always stored on the blockchain, that's the same with Ethereum or Bitcoin. The pass phrase gives access to them.
If you lose your pass phrase, you lose your coins forever.