Writing file logic and setting up a Micro service can be done quickly. I could send you a link to a video I created showing setting up a service starting point in a couple minutes.
The micro-service has the added advantage in that if you branch out from FileMaker, per your reply above, the micro-service lives on! IMHO, the micro-service approach is the best "future-proofing" you can do as it does not rely on FMP at all.
However you decide to go, I wish your project success. 
Thanks for posting back.