Oh, never mind, it looks like it cannot be used with namespaces & multi-tenancy. Our use case is our employees have an org identity center federated from our corporate Okta all in the default namespace. Then we have customers in their own namespaces that are federated from our customer Okta.
I would love to be able to use the identity center solution for our employees as it would let us create single author/admin pro users and use them across all of our AWS accounts, but it doesn’t look like we can do that yet 
It would be nice also to simplify group management for our employees.