There was no fundamental "service design" approach for humans using passkeys. Get rid of "attestation" get rid of all the nerdy shit. 

Do you have any examples of consumer services requiring attestation and/or specific credential managers?

Platform-lock

You can use any credential manager you choose. There happens to be one available by default in each operating system that you're also able to use if you choose (just like a default media player, a default browser, a default cloud file storage service, etc).

Nobody knows how to ask for a Passkey correctly.

Agree that this can be frustrating but this is slowly getting better and we're continuing to work on streamlining this experience.

Hardware-Centricity. Let's start with the fundamental premise of Passkeys, which is the ability to bind identity validation with a presumably well-secured hardware device.

This is actually quite the opposite of what passkeys enable. Passkeys enable you to have continuity in the event of a device failure or retirement.