Just about every 8/S8 reel of more than 150 ft is likely to have sections with bastly different exposure too.
Controlling every possibility is hard, and there will always be something else. In the mindset of Kinograph, it may be appropriate to setup a framework for common control of different devices, as a layer that individual devices can connect to, and ultimately have a software that uses this common framework for scanning.
I have been thinking along those lines for the 8/S8 built. In that context (home film, poor splices, varying exposures), it makes sense to have a simple protocol for light and transport to a usb port. I’m leaning towards using a raspberry pico (an arduino would work too). Basically the transport and light becomes a box with a USB port.
In the same manner, the Camera can be another section. The context here is stop-motion. And in that context, the camera is already boxed. For those without the budget for a machine vision camera (like me) the alternative over a raspberry HQ may be a mirrorless camera. Both may be controlled via python (the mirrorless via gphoto2), allowing everyone to create their own front-end for the specific purpose of the scanner particulars.
But for those just starting, if there was a ‘box’ that solves the light driver and transport control would be a huge leap forward for opensource builds.
Agree with @friolator that making the same for all possibilities of continuous motion adds much complexity, but for a constrained build like Kinograph there may be a path forward.
Food for thought.