Part 8/13:
Blockstream Jade Plus: Fully open source.
Cold Card Q: Fully open source firmware, verifiable and auditable.
Bit Key: Open source, with verifiable codebase.
Air-Gapping Capabilities
Air-gapping enhances security by isolating private keys from connected devices:
Treasure Safe 5: Cannot airgap; always requires wired connection.
Ledger Flex: Not entirely airgap; uses Bluetooth which is not truly airgapped but offers wireless convenience.
Blockstream Jade Plus: Fully airgappable via QR codes and microSD cards, despite having Bluetooth.
Cold Card Q: Fully airgappable supported through QR codes, NFC, and microSD.
Bit Key: Entirely contactless via NFC, making it inherently airgapped.