Pending Green Card applications are going through "extended vetting", which I understand means resubmitting biometrics against an FBI database which now contains more nationwide data. Do you know anything about this process?

They've always had nationwide data. The database is NCIC. It's an imperfect database that has hits for any interaction with law enforcement. USCIS/DHS/State routinely use this database. So there's not much that's new there.

Nothing has been announced yet. USCIS indicated that these expanded background checks shouldn't delay the process by much but of course no one knows. Right now, it's just wait and see,