Maybe things changed, but I recall rapleaf had a service where you enter an email address and you could receive a facebook id.
https://www.rapleaf.com/
If something was not in there, one could "sign up" with the email, and it should have a chance to get the data after a while.
I came across this when using a search tool called Maltego a few years back.
The app uses many types of "transforms", and a few where related to facebook and twitter etc..
..or find some new sqli's on fb and fb apps, hehe. :)