While it’s not entirely clear if Jay-Z makes a habit of not signing things he’s not directly affiliated with, a quick Google search didn’t seem to dig up any off-beat items that claimed to have his signature attached.
The rapper famously responded that while he couldn’t play guitar, he’s still a rock star.
The closest thing that could be considered questionable would be a guitar, which is still related to music.
Plus, it could be a reference to the rapper’s famous spat with Oasis’ Noel Gallagher, who criticized the decision to have Jay-Z headline Glastonbury in 2008.