I have recently used Cobo Vault and Parity Signer as air gapped wallets that use QR code’s both ways. Read the transaction, offline signing, and then use the camera to read the signed transaction for signing. It’s an extra step compared to Anchor Link, but much easier than a regular hardware wallet. I use an old device with WiFi, etc disabled.
Has anyone done this with eosio?
Anchor Desktop has this feature, but it’s a process using a saved file transferred via USB as opposed to scanning QR codes.
The difficulty in EOSIO is that you often want the ABI and contract data on the cold wallet, which can’t be retrieves since it’s offline. It’s required on the cold device if you want to be able to read the transaction and its data, so you know what you’re signing.