Go cheap on the mattress topper and mattress pad. Trust me.
When we arrived that Spring to pack our son up to come home, his topper was disgusting and went right in the trash. Same with his room rug. It looked fine and clean on the top, but once we rolled it up you could see stains on the backside...ick. Also, I'd do a cheap comforter over a duvet cover. I know 100% my son's comforter never got washed that entire first year. We may have even tossed it before packing him up but I can't remember that one for sure.
Boys need/require so much less, too. My son didn't care at all about his colors or decorations. He just told me to buy blue.
Shower shoes
Shower caddy
Some kind of secured box he can keep valuables in if he'll have any there
Rolling cart - great for keeping snacks in and we found one that had a bottom drawer that locked, so it was great for valuables.
Also, my son saw guys wearing these in the showers and bought some and loves theme. This is not something I'd have picked or thought about for him at all.
https://tinyurl.com/9yvpp44n (sorry, it was a long long long Amazon link)
Stuff we bought that he never once used:
Coffee maker - he got it each morning for "free" at breakfast or bought one from the coffee cart
Printer - was even on the list of tech needed & he never once had to use it
Body pillow
Extra set of sheets - they were never opened
Extra blanket
Stapler & other office supplies
Umbrella
Handheld vacuum