Guys do not wear bathrobes. I checked with some male college students. They wear gym shorts and a tshirt. Or towels.
We are starting to set aside some of the toiletries. We have so many bottles of free shampoo, bars of soap, tubes of toothpaste and toothbrushes, deodorant… so it’s mostly clothing and household items he will need.
School supplies! As homeschoolers, we just didn’t do a lot of “school supplies” shopping. And, of course, we don’t really know what he will need. Notebooks and pens to start with, I suppose. I’d better track down those experienced college students again and ask more questions.