Microflows (MF) and Nanoflows (NF) in Mendix are model elements rather than separate source code files, so you won’t find them as .java, .xml, or .json files in your project directory. Instead, all of the application logic—including pages, domain models, microflows, nanoflows, and security settings—is stored inside the Mendix Project File (.mpr). This .mpr file acts like a database-style container that encapsulates the entire application model, making Studio Pro the place where you can view and edit these flows rather than browsing them directly in the file system.
I hope this helps