The other issue is sharing Passkeys. My wife and share passwords for our bills, how can you do this with Passkey? You can't.
Yes, you can share Passkeys with your wife or as many people as you want. You can AirDrop a Passkey to people you trust. Their own authentication then works without your intervention.

That said, best practices are for sites where multiple users are likely to need access such as banks, utilities, video streaming etc to have managed Access and Permissions by individual. You are you, your wife is your wife. You shouldn't need to have the same login. Instead, in your account's access and permissions, both of you should be designated as people who have access and permissions to do things with your own profiles.
I hope passkeys remain optional forever. It sounds like a system that requires having a mobile device on you at all times, I'd hate to keep unlocking my phone just to log in to a website on the desktop. Having a password manager is so much simpler.
Where do you have the password manager? On your computer? Then your computer will have access to the Passkeys without the phone. A Passkey doesn't just exist on one device. It can be shared to different devices.