Thank you for confirming this. Currently, that isn't built out inside Fabric, but it's good to know you'd love to see this added in. All our efforts are currently focused on the upcoming migration from fabric to firebase. If you want, you can try migrating to FIREBASE where, We are integrating the best of Fabric into Firebase to give you one powerful platform including SSO.
Give it a try and let me know, if you have any questions.