Passkeys shared between different apps

I think there are two related questions here:

1. Can passkeys created in an app be used in the associated website in Safari (or vice versa)?
2. Can passkeys created in one app be used in another related app?

The answer to both is yes! In order to use passkeys in apps, you must use Associated Domains with the webcredentials association, to create a two-way link between your app and website. The relyingPartyIdentifier that you use with a passkey request needs to match your association. All apps associated with your domain will be able to use the same passkeys, and the same passkeys are also usable on that domain in Safari.