Passkey registration and authentication on iPhone using native application on top level domain and subdomain domain

Hi,

Is it possible to use top level domain registered passkey(example.com) to authenticate against the subdomains (my.example.com)?

If yes, how it should be handled at -How it should be handled at associated domain level (https://developer.apple.com/documentation/xcode/supporting-associated-domains)?

Passkey registration and authentication on iPhone using native application on top level domain and subdomain domain
 
 
Q