Passkeys for Bitwarden Two-Step Login cannot be stored in your Bitwarden vault. They would have to be stored in a third-party authenticator (e.g., either a hardware key, or one of the passkey authenticators available through Android, iOS, Windows Hello, etc.).
Bitwarden provides a Two-Step Login Recovery Code, which is a one-time use code that disables all forms of 2FA on your account. Therefore, when using the recovery code, you will be able to access your account even if you no longer have your Two-Step Login passkeys.
Please note that if you ever do need to use the Two-Step Login Recovery code, it is important to immediately re-enable some form of 2FA that you still have access to, or else you may run afoul of the upcoming “New Device Verification” requirements. Another caveat is that because the recovery code can only be used once, you must save a copy of your new recovery code as soon as you have used the previous code.
You should keep a copy of your Two-Step Login Recovery Code on a so-called “emergency sheet”, and you should bring a copy of the recovery code with you when you travel (perhaps tucked into your passport).
Let me know if you have other questions.