I’m just now starting to really look into this since our eldest is now twelve years old. We do unschooling if our home, which is a form of self-directed education, so my focus has been on those experiences.

Here’s an research paper about Grown Unschoolers experiences with higher education, page 38 discusses admissions: https://www.othereducation.org/index.php/OE/article/view/105...

And here’s a reddit thread about homeschoolers getting into Purdue (which is the school I went to): https://www.reddit.com/r/Purdue/comments/bszc3i/have_any_hom...

I’m assuming that each school is going to have their own criteria.