That's not quite correct. This can easily be seen by simply considering that the people who developed the passkey standard are also developing a passkey import/export standard which is nearly done and implementations are appearing in the field already.

For example Apple's Passwords app on MacOS/iOS/iPadOS 26 now supports export and import of passkeys to/from other apps that support that standard. I don't know if any other apps have yet actually released such support.