Yea, I believe they try to convince you to send your phone number associated with facebook account. Next they try to reset your password. When fb sends you the 2factor code, the scammer will claim they're sending you a code to text back to them so they can verify that you're a real person...I remember reading somewhere about not divulging a cell phone number when using Facebook marketplace unless you are certain it’s a legitimate seller- not exactly sure why but for the most part the Facebook messenger seems to work sufficiently so I don’t use my cell #/ text.
Fwiw