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.
We have the following use case, we have MS 365 for our employees, we also have consultant services which have their own MS 365 account, we cannot collaborate because it is two different account. Ultimately both parties have proper subscriptions with MS. So yes we are interested in adding people outside our own MS account