This feature request is working its way through the backlog queue. No new details are available yet.
-WarrenFrederik Devreese commented
Adding documents to a team: when editing the document (online), you end up in Sharepoint. So why is this 'teamsite' not visible/reachable via Sharepoint Admin Center - Sitecollection ??
We know you are patiently waiting for this feature. This feature is being implemented in stages. Fast tenant switching is currently in testing both internally and with early customers. We expect to release to the public in the Fall. I’ll post an update once it’s rolling out.
Full multi-tenant, multi-user support will be added after fast tenant switching.