The necessity to protect the (cleartext) seed QR is a pretty huge downside of this system. You can't even know if someone copied it, since you always carry it around in clear text.
While a quick picture of the QR gives the attacker full access, as well as the ability to stay unnoticed
That's what passphrases are for. You can also write your seed in different ways, formats, number bases, encodings, encrypted, but sure this is not for everyone. Most people should just trust companies and go with mainstream solutions.
Krux has a supporting role in sovereign strategy, it's a Swiss army knife for create and load seeds in a variety of forms and to sign PSBTs and messages, it requiring less trust.
Can Krux be used in multisig setup with other hardware wallets?
Yes!