By default on all M0090 variants, all the transceiver/buffer circuits which take the 1.8V Kernel Debug UART to 3.3V TTL for J6 are DNI'd (not populated).
The only thing that can be done is to probe on raw circuit pad locations for TX and RX to get the signals at a 1.8V level.
Here are those snapshots to help guide you should you wish to pursue that route:
However, the ICs are located on the bottom side of the PCB, so when mated with Voxl2, you cannot probe directly, which would require soldering on wires to the PCB pads. That would likely violate any warranties on this specific PCB if you did that.