According to this forum post, only one of the USB-C ports (J82) is known to work in host mode: One USB-C port not working on THOR
However, on my unit when I plug in a USB-C storage drive in J82 no events get logged in dmesg and the drive is not recognized. Only USB type A ports work. TLDR: USB-C ports only supply power.
This is a brand new unit. FW is 38.2.