I assume the issue has to do with licensing as opposed to the brands' respective interest.
There's some pretty nice and obscure stuff out there like the Streaker Peanut's collection.
Step into sports history with the Peanuts x Syracuse Snoopy's Football Team Tee. Crafted with premium materials for ultimate softness and durability, this tee brings iconic characters to life in vintage-inspired style. Get yours now and join the exclusive collegiate collection!
www.streakersports.com
My guess on the '47 and Nike stuff OP wants is that they aren't willing to share as much revenue as SU wants, actually spinning the logo onto hats is easy for them.
Also, thanks. Now that I've found that Snoopy shirt to make a point, I must have it lol.