I use Bitwarden for critical passkeys. Most people do not. Passkeys, as currently implemented, for the vast majority of people, do not allow for effective back-ups in ways the user controls. You can't back up the keys from your iCloud and then use them on your friend's Windows PC to access something when you lost your iPhone. You can do that with passwords.
> You can't back up the keys from your iCloud and then use them on your friend's Windows PC to access something when you lost your iPhone.
Just enroll a second device like a hardware token. Then plug your hardware token into your friend's computer and you can log in to sites on your friend's PC without having to copy over and unlock your entire password safe.
I am. I'm not convinced that this will allow me to back up passkeys in any way. I wouldn't be surprised if Apple were to allow you to transfer passkeys out in such a way that they don't work on the original device anymore, which would make this standard irrelevant for what we're talking about.
If you specifically want a file you can control you need to use other passkey software, like bitwarden. Which you already mentioned? Huh.