Not all FP scanners are capacitive, some are optical scanners.
The optical ones will capture an image, a small one, not sure how much use it would be for film
It's been a few years since I retired but before then I was a software engineer and the applications I wrote integrated fingerprint capability using off the shelf FP readers from Digital Personna and Lumidigim, along with their respective SDK's.
At first we used capacitive readars but when we switched to optical readers I noticed that MS Windows showed the FP device as a camera in Device Manager. That intrigued me so I played around scanning things other than fingers. I can't remember the resolution but I don't recall it being that high. We saved fingerprints as digital data, either proprietary or FP standard and I recall the SDK had options to save as image type formats.
Such scanner employs the ridges structure of the finger skin. Photographic film rarely has a relief, and sure not such of effectively equal height peaks.