A potentially good idea got corrupted by vendors, password managers, browsers, etc trying to assert control. I'm also an engineer and I find the UI around passkeys entirely unclear, but it doesn't have to be that way. It seems like everyone wants to be _the_ password manager for all your passkeys. They don't want to make it easy to understand that is what they are doing though, they just happily offer to "handle it for you".
My non-technical friends are extremely confused by passkeys and if they should use them and how to use them and I honestly don't have very good answers. It is a mess. I don't believe an inherit mess, but one created by the companies and projects trying to take advantage of the new system.
> It seems like everyone wants to be _the_ password manager for all your passkeys.
Which defeats part of the point of passkeys in the first place in that they are supposed to be device-bound, the private key held in the TPM or secure enclave or whatever other security chip, mathematically non-exportable. Storing all your private keys in a cloud vault still leaves you exposed to potential credential theft if your vault gets compromised.
Every device is supposed to have its own unique private key, stored in TPM, released only when passing the user challenge (biometrics or pin, or a yubikey).