I managed to squeeze quite a lot onto this thing. It has a sturdy USB-C port sunk into the board to minimize the thickness. Beside the port are 2mm slots for the device to be screwed down. The port also portrudes past the PCB edge for flush panel mounting.
The antenna is among the smallest available.

The board also has a few protective features such footprints for TVS diodes or varistors on the USB data lines and power input, a 500mA fuse on the USB power line and two ferrite beads to reduce noise at the main input and the analog reference.

The microcontroller is connected to a bare metal patch on the backside to make a heatsink more efficient if it's required.