Most sites that allow a passkey also require you setup 2FA with your password when enabling passkeys. Which, unless you also set up an alternative method like

Most sites that allow a passkey also require you setup 2FA with your password when enabling passkeys. Which, unless you also set up an alternative method like TOTP, would also be your passkey. So ironically, your options would be your passkey, or your password+passkey/FIDO key (in 2FA mode).