Son going to college in different state?

I have a less usual situation: instead of my son going away to college next year, my entire family is planning on moving to another state. We haven’t figured out where, but he would like for us all to move together and he can just go to a school nearby. We are starting an entirely new life. How then, does instate tuition work? We won’t have been there for 12 months, by the time he’s enrolling. Would he need to wait to get discounts? How does FAFSA and tap and pell work, is it federal so it doesn’t matter which state? It is so challenging having to factor in these things and which college he’ll go to, and still land somewhere within the vicinity and make all the pieces come together.