Moon on Nostr: Seedsigner (stateless, no secure element, hard airgapped) Foundation (secure element ...

Seedsigner (stateless, no secure element, hard airgapped)

Foundation (secure element - Passport Pro Quantum-Link airgapped, Original Passport hard/physically airgapped)

Jade (virtual secure element - blind oracle on Blockstream servers…, not airgapped but “can be used airgapped”)

Bitkey (secure element, but native technical / social multisig design, not airgapped)

Also all the above projects are open source. Even if you roll your own keys you will need to trust the software inside the HWW for checksum computation.