Just to reiterate what was stated above, Krux was designed to be a hardware signer for multisig wallets, and relies on coordinator software (such as Specter Desktop or BlueWallet) to generate PSBTs that it can sign to send funds out. It isn't really a 'hardware wallet', it's much simpler.
This is inconvenient, but this was by design to decouple the hardware from the keys in a multisig so that:
1) you can have less hardware devices than there are keys in your multisig (saves money), and
2) you don't have to worry about safely storing your hardware devices in addition to physical backups of your keys, or have to worry about bit rot.
Basically, Krux is designed to be used with physical copies of your keys that you obtain after traveling to various geographic sites you have them stored at, hence all the different supported ways of inputting your mnemonic (as text, numbers, bitstrings, QR codes, etc.); I wanted a device I could use to input a key directly from a steel punch card without having to do a conversion, for example.
The QR code input method offers a compromise by making the 'login' process a lot faster (near-instant reads once you have the camera lens honed in), but it requires that you create one which isn't the safest thing to accomplish. To solve that, Krux itself can print one out for you when you attach a mini thermal printer to it (probably sounds more intimidating than it is! see here: https://github.com/jreesun/krux#printing-qrs). The downside to this is that you now have an extra copy of your mnemonic to safely store, but the upside is that you can always just burn it and make another. Alternatively, you could technically have the printed QR code be the only copy of your mnemonic, though I wouldn't suggest it since it could fade over time or if exposed to heat. If only there were a $50 laser printer one could use to etch a QR code into steel!
so every time you turn it off from power you will wipe his memory, and you will have to import your key every time you turn it on.
This is inconvenient, but this was by design to decouple the hardware from the keys in a multisig so that:
1) you can have less hardware devices than there are keys in your multisig (saves money), and
2) you don't have to worry about safely storing your hardware devices in addition to physical backups of your keys, or have to worry about bit rot.
Basically, Krux is designed to be used with physical copies of your keys that you obtain after traveling to various geographic sites you have them stored at, hence all the different supported ways of inputting your mnemonic (as text, numbers, bitstrings, QR codes, etc.); I wanted a device I could use to input a key directly from a steel punch card without having to do a conversion, for example.
The QR code input method offers a compromise by making the 'login' process a lot faster (near-instant reads once you have the camera lens honed in), but it requires that you create one which isn't the safest thing to accomplish. To solve that, Krux itself can print one out for you when you attach a mini thermal printer to it (probably sounds more intimidating than it is! see here: https://github.com/jreesun/krux#printing-qrs). The downside to this is that you now have an extra copy of your mnemonic to safely store, but the upside is that you can always just burn it and make another. Alternatively, you could technically have the printed QR code be the only copy of your mnemonic, though I wouldn't suggest it since it could fade over time or if exposed to heat. If only there were a $50 laser printer one could use to etch a QR code into steel!