In a post to tech@, Jan Schreiber submitted a driver for USB network control mode, uncm(4). Jan writes:
I noticed newer Android devices (since Android 6 if I'm not mistaken) do not use urndis(4) for USB tethering any more. They now use CDC NCM which is missing a driver in OpenBSD. Below is my first go at it. I moved some defines and structs out of mbim.h into usbcdc.h to not include everything for mobile broadband. (No functional change for umb(4)).