Can I ask the recruiter what I can work on for interview next time?
When I last interviewed at Facebook they gave me this information before I even asked. That was a few years ago though.
I got some feedback but not final feedback
They do tell in general if you have done bad in coding or if your design interview was not upto their expectations
Is this onsite or phone screen?
FB is the only place I got real feedback
I asked and got real feedback. I made it to onsite before they said no.
Never hurts to try but I believe their general policy is not to divulge anything, unfortunately.