I recently made a post #781431, where I used Sparrow and NUNCHUK to create an OnlyWatch wallet, in which a transaction is signed in Sparrow offline and transmitted with NUNCHUK online. This is an alternative for those who for some reason do not want or cannot have a Cold Wallet (Hardware Wallet).
On this occasion I propose to do the same but only using NUNCHUK. So whoever does not have a computer or has a mobile phone that they no longer use can have their stashes in a somewhat safer way.
We start by installing NUNCHUK on both phones.
On the phone that we do not use, which will also be OFFLINE ALWAYS, we are going to create a new wallet. With NUNCHUK it is as simple as saying CREATE HOTWALLET and that's it. You can edit the name later, but you already have a wallet with its key. It will appear in Orange, that means you haven't saved your seed yet, so I advise you to do it and make sure it's safe, IT'S 24 WORDS.
Now it's time to create the OnlyWatch. To do this, in the created wallet we go to VIEW WALLET CONFIGURATION and touch the three dots in the upper right corner and select EXPORT WALLET CONFIGURATION. We have several options, I recommend using BSMS, which creates a file that we then import into the phone we're going to use to transmit, or use QR BC-UR2, which we scan with the phone we're going to use to transmit.
We go to the phone we're going to use to transmit, the one that's going to be ONLINE. In the same way we CREATE a new wallet, but this time with the option RECOVER AN EXISTING WALLET. Here we use Via QR, in that case we scan the QR that is being generated on the first mobile and that's it. If we use Via BSMS, we will have to send the BSMS file that we have saved on the first phone, it is recommended to use Bluetooth or USB. The file is imported and that's it, we already have an OnlyWatch wallet in our NUNCHUK.
This option, I repeat, is for those who for some reason CANNOT or DO NOT WANT to have a cold wallet. So you can create a transaction in the OnlyWatch wallet, then export via PSBT or QR file, the transaction to the wallet that has the key to sign, return the PSBT file to the mobile that is online and transmit the transaction.
READY, it's that simple. The good thing about NUNCHUK is that in addition to being able to do all that, you can even select the Coin that we are going to use for each transaction, something that other applications for OnlyBitcoin Wallets also do, is that with NUNCHUK YOU CAN DO IT AND LEARN IN TESTNET.