It's pretty minimal, at the moment only connect.facebook.net, connect.facebook.com, pixel.facebook.com, and apparently facebookinc.122.2o7.net. If I had to rely solely on it I'd add a lot of hosts and in particular known ones under fbcdn.{net,com}. In contrast, DNS and IP blocking is extensive.
https://github.com/jmdugan/blocklists/blob/master/corporatio...