COLDCARD

From Coinkite, makers of OPENDIME, Coldcard Wallet Ultra-secure & Opensource Hardware Wallet for Bitcoin. The only dedicated air-gapped solution. It's a Bitcoin hardware wallet, so it signs transactions and can be used offline. BIP39 based, which means you can backup the secret words onto paper, and have lots of sub-accounts and unlimited independent payment addresses. Now with BIP39 passphrase support, unlocking up to 5.9e197 additional wallets from the same seed words! It knows how to understand transactions, so you can see what you are approving. The first "Partially Signed Bitcoin Transaction Format" - PSBT (BIP 174) native wallet which can be used completely offline for its entire lifecycle. See HWI for Bitcoin Core support!