How do you see passkeys as a walled garden but not 2FA? You presumably store your 2FA seed in a password manager.
Even if you throw your phone into a volcano and buy a new one, you can still receive SMS verification.
Passkeys only very recently got relatively broad support for migrating data (after years of promise and no support at all), and they report (optionally with hardware attestation) what password manager you're using so sites can force specific ones.