Is it possible to create trusted functions on a tablet (Android or iOS)?

Is it possible to create trusted functions on a tablet (Android or iOS)? I want to allow the user to click a button and it will save the form to a specific location, with a filename based on a couple of fields on the form. The button calls a function in the AppUser directory, because it needs to be a "trusted function." This works for Desktop (Windows). Can I create this functionality for an Android or iOS tablet?