XCP-ng (an open-source hypervisor based on XenServer) has been supported in CloudStack for some time, and support for XCP-ng 8.x will be available from CloudStack 4.15.
From an operational perspective, there is no visible change in the UI or API – XCP-ng 8.x hosts can be added to CloudStack during zone deployment or by using the addHost API / UI. With guest OS mappings added for XCP-ng 8.x, once added all VM operations can be performed on such hosts just like any older XCP-ng hosts unless they are functionally not available on XCP-ng 8.x. It should be noted that with XCP-ng 8.1, support for paravirtualized (PV) VMs has been removed, therefore PV guests and older guest OS will not work on 8.x hypervisor hosts. More information about supported and removed functionalities in XCP-ng 8.x can be found in the XCP-ng documentation.