Agree with Wieke. Further adding to it, if both options are not available then you can place the import files in your resources folder (project root directory\resources) and in your after startup microflow you can use java action ‘GetFileContentsFromResource’ from community commons to get contents of file and further process it (get each file from resources folder based on file name and process it). Note that your application statup will be slow.
Hope this helps!
Where should the data come from? If the files or data can be accessed using a service, or are the files reachable from a database? If so you could make a restore or upload part of your after startup microflow, initializing your environment.