I am working on setting up a content type hub for my SharePoint Online environment. Is it possible to unsubscribe a certain subset of site collections from the content type hub? We would like these content types available for most but not all site collections. I do not believe this is possible on-premises, but was wondering if you can do it online.
I've tried this before and it isn't possible - there is only a feature to designate a site collection as a content type hub, not as to whether it is a receiver of content types from the hub.
(As an aside, don't try changing the CTH location in SharePoint Online, it causes all sorts of headaches. As a general rule things that aren't possible in on-prem are likely to still be impossible in SPO.)