On a past project, I used the FSYNC input on the MPU-9250 on the (now retired) 14001.
I noticed, on the OpenLog schematic, that the ICM FSYNC appears to be N/C. Is that true? Is it not connected?
If it is not connected to GND or VCC, then I can get in with a hot-air gun and run a wire to it.
If it is connected, well, hacking it becomes a bit trickier, but still possible.