Can't find Sansa Fuze Device on linux

[bugbert]

I'm using Linux, (NixOS if it matters), trying to install rockbox on my sansa fuze +

The device is there, /dev/sdd1. I can mount it if I want and look through the files, I even changed the permissions to rw for all users (I tested that I can cat it unprivleged).

Thanks in advance for the help!