Passkey Account Abstraction signer

Passkey Signer is a proposed signer package for account abstraction smart contract wallets that uses passkeys, so users can log in and sign transactions with device authentication such as Face ID, Touch ID or passwords. The package would extend ethers' abstract signer, with the authors crediting @nlok5923 and @0xjjpa for work, reviews and discussion. The article says passkeys avoid seed phrases and private key management and resist weak, reused, leaked or phished credentials. Listed drawbacks include significant on-chain gas costs for signature verification, which Opclave addresses with a custom rollup using a "secp256r1 verifier" precompile, and device dependency, which iCloud Keychain backups and multi-device owner support are meant to mitigate.