As I mentioned in the article, ServiceNow will initially release a MSFT Sharepoint connector.  If you need to move to AI Search today and connect to other external sources please see the below for more details on the 45+ connectors to AI Search.

AI Search + Raytion enables our customers to integrate 45+ third-party information systems in ServiceNow applications and deliver a truly unified search experience.
https://www.raytion.com/availability-servicenow-ai-connector.html