Hi Nikhil,
Sorry for our delayed response on this. I just recently joined our forum to help out with more HW centric question.
As Chad mentioned, this does require HW mods if you do not want the SW driver timestamp method (which would be our recommendation/preference).
The Lepton signal VSYNC (on GPIO3 most likely is what you are referring to) is running at the VIO voltage of 2.8V to 3.1V per Lepton specs. Our camera sensors are MIPI based, and as such all of those I/Os are at 1.8V, so a level translator would be required which makes connecting these a bit tricky, especially if you need bi-directional support with another sync controller/snoop device. This would need to be something done on a custom interface between the Lepton and the stereo sensors. We do not have such module but would be happy to give further guidance if you need it.
Thanks!
Vinny