InvitedBy information in Azure AD Portal or Graph API

I'm looking for an "easy" way to get the inviting "object" (user, app, ...) for an B2B user object (userType -eq "guest"). The only information available regarding this typ of data is the Azure AD audit logs. But I really would like to avoid checking the audit log for the specific user object. The retention period and also the delay until the data is available in the audit log are some big pain points.

I've checked serveral docs regarding B2B invitation/redemption but without luck. I really would love to see an property on the user object like invitedBy:GUIDofINVITINGuser

https://developer.microsoft.com/en-us/graph/docs/api-reference/beta/resources/user

But nothing in the beta version of the graph.

Next stop was the invitation manager:

https://developer.microsoft.com/en-us/graph/docs/api-reference/beta/resources/invitation

Also no luck, because this can only create invitations and not enumerate pending or completed requests 😞

This is a stackoverflow question with a similar request and "negativ" outcome:

https://stackoverflow.com/questions/44184587/check-redeem-status-of-directory-invitation-through-microsoft-graph

Is this a roadmap thing? Do i really have to query the Azure AD audit logs that are also not available in the MS Graph API?