Technically, it is called “Live Assist for Dynamics 365 Powered by CaféX” (hands up who prefers “Web Chat”) and is now available on AppSource.
Full details of the announcement are available. As per AppSource guidelines, there is a free trial and a video walkthrough.
This app will allow you to embed web chat operator panel within web client and Unified Service Desk. As for the client side, during the configuration process you’ll be given a script to paste into your web site (which does not have to be portal, in case anyone is wondering) and the chat widget will magically appear.