You can, just like you can store your TOTP key in your password manager to have the security of 1FA again. A site that doesn't want you to could try to use att

You can, just like you can store your TOTP key in your password manager to have the security of 1FA again. A site that doesn't want you to could try to use attestation certificates to force you to use a real vendor's keys which should never be extractable.