When we were searching, we did run into a couple of schools that gave $1000 or so just for filling out the FAFSA. I think one was Stetson, and there was another one in the south. They wanted everyone to fill them out and sort of publicized this, so I think you’d know if a school was doing it.
Last year some schools gave a Covid fund payment to all students who had completed a FAFSA. The federal government gave schools millions of dollars and some schools gave it back to students, even students who hadn’t received any other aid or taken the loans.