If you follow the Helicon products you'll see they had a pedal for guitar called G & a pedal for keys called M. They updated the G to GXT but did not update the M. I think it's a matter of time before the M is discontinued and the G & M are combined.
Hiya bobseekone,
It will show up as a device because MIDI is used to transmit updates over USB but Harmony GXT is intended for manual footswitching only, as such there is no MIDI patch change ability. There are a few people who use MIDI foot controller boards so we'll put this in the wishlist!
Best wishes,
Joey