With the upcoming January release, you can use the Data Studio sharing option to make your segment data available within the Marketing Cloud application.
Where: Sharing options are available in the licensing step within the Data Studio provisioning window.
How: Customers can share or sell their segments using the Data Studio sharing option to make the segments available for use in Marketing Cloud. Buyer or receivers of those segments can overlap with their own 1st party data sets, and activate their users into Marketing Cloud.
For information about Data Sharing Access, see https://konsole.zendesk.com/hc/en-us/articles/360024274173-Data-Studio-Sharing-access.