There have been no whisperings of that being the case with this Luke Cage casting, though, so this is most likely just a new character meant to add more depth to Misty’s story in the new season, while possibly kicking up narrative dust for other characters as well.
One guess is as good as any, since Nandi Tyler will be a character unique to the Marvel Universe, with no established canon in the comic book world.
Of course, Marvel has been known to use false character names during the casting process, as to not arouse any suspicion that characters may be more important than they initially seem.