I am currently an international student but my parents are working on getting a green card. I was accepted to boston university and I didn’t get any financial aid. If I get a green card before the summer, could I possibly get some money in freshman year or maybe at least in sophomore year?
You need to ask BU about their policy about aid for students in that situation.
If you do get your green card, you will be able to file the FAFSA and get a student loan - even for this fall. If you are low income enough, you will get a Pell grant. But if you are low enough income for Pell, you certainly can’t afford BU without significant aid, so it would have been crossed off your list long ago.