USB C socket on backsude of control board

Is the USB C connector next to the OCuLink socket usable? I tried to plug in a USB stick, but it was not recognised, and its LED did not light. Neither do I find a corresponding menu entry in LuCI, nor a device file in /dev/bus/usb.

This part is reserved for external hosts. Currently, these two interfaces are not open.

External host = a computer, which then steers the control board?
Currently not open = might get “opened” in the near future?

I’d like to attach an SD card reader to the cluster box, so I’ve gotta use a connector on one of the blades, right?