Startup Idea: File Synchronization Tool between Cloud Storage and USB

Startup idea to develop a software that helps in synchronizing files between a college instructor's cloud storage and a USB drive. The tool should be able to identify the most recent versions of files, flag differences and offer integration options.

I am a college instructor. I use cloud storage (OneDrive currently) to store PowerPoints for my classes so that I can work on them seamlessly between my home laptop and office computer. Then I transfer the .ppt on to a USB drive to take into the classroom. My pain point is that occasionally I'll make small alterations (correcting typos etc) on the USB version of the file, but I rarely remember to transfer it back to the OneDrive folder. As a result, when I go back to the .ppt next semester, the typos are still there in the files stored in the cloud, which are the versions that I'll be updating for the new semester.

It would help if there was some piece of software that checks USB drives for files with the same filename as files stored in a specified local folder every time a USB drive is plugged in. It would alert me if there's a more recent version of a file on the USB. Even better would be if the software could flag the differences, and even offer me options for integrating the different versions.

I would potentially pay for something like this, but probably not more than a few dollars.