Hm interesting. I think i've heard something about this - let me try to dig that up

I figured it out! The units that ship from DigiKey come pre-flashed with RAK's RUI3 bootloader on them, so the "double click for DFU mode" doesn't work out of the box. I had to cobble together a serial debugger out of a raspberry pi and manually re-flash the bootloader before I could continue.