Is there any Azure B2C end-user queryable endpoint that will allow that owner to identify which tenants they have authenticated to?
A dashboard for B2C users that is an aggregate of all tenants they have federated with? Is there some extension of the /common endpoint I could make an OAuth query to? (ideally including AAD B2B guest accounts)
4/24/20 Edit:
I found this in the portal that implies a portal is available.
I'm looking for the API in which to programmatically add applications to it before a migration.
I need to have the applications already 'signed in' or linked to applications I own in the B2C directory (OIDC/SAML2 apps)
Your question is the equivalent of asking, "Can i find out if i registered at StackOverflow and Facebook with this/my email?". You cannot do this, AAD B2C is isolated tenancies representing a single organisations' identities. There is no equivalent of /common endpoint for AAD B2C. In AAD and AAD B2B accounts, there is a mapping created from the original account to identify which tenants they are in. This is to maintain a single identity across the Microsoft ecosystem. In AAD B2C, this doesn't exist, goes back to my first sentence for 'why', they are separate applications, and inherently have no relationship, nor do the identities.