Other extensions can provide other event types, condition types, and exception types, but currently, the Core extension is the only one that I know of that does.
This just means the Facebook extension doesn't provide any conditions. But you can absolutely mix and match within a rule and pull events and conditions from the Core extension, but use an action from the Facebook extension.
As far as I know, in Events, Conditions and Exceptions it is only possible to use the Core Extension. Just the Core Extension has useable types to use, but also the types of e.g Analytics. So with the Core Extension you could build a condition like "pageviews > 10 in current session".