@Alex-Kushleyev we needed three outputs and three inputs, so we ended up using an entirely different board (an AVR system) connected to the VOXL2 via ttyHS1 through the expansion board, and that seems to be doing what we need, with the added benefit of the pulldown resistors being built into that control board. There is certainly something odd about the PX4 build on this unit, both in terms of available camera controls and GPS options, which is the next thing we're trying to tackle.
@restore unfotunately I'm under an NDA and can't say much about what we're doing with the Sony hardware, but I will say that their documented processes for the Raspberry Pi 4 also work on the Voxl2, as long as you have the USB3 available. Try not to use the SDK to trigger the camera though; the performance there isn't exactly consistent. The hardwired options (be it through the not-quite-USB port or the phsyical interface on something like an ILX-LR1) are rock solid, but as they're designed to be button-triggered, you'll need a resistor between your control board and some sort of transistor (2N222) and then control the actual interface with the transistor. Otherwise, the trigger input is looking for the output from its own source, which is an indeterminate voltage and will quite likely damage the VOXL. The transistor will take essentially whatever current you give it, so that resistor is also mandatory - 10kOhm works for me with the AVR 440 chip controlling it.