Currently the mobile app downloads full file in order to render its preview. This is time consuming and megabytes of data are transfered unnecessarily. The generated preview is even not cached so you have to download the full file over and over if you skip among multiple files during a day or session.
Why the app can not use a file preview like it is in browser? And offer file download only when user does need it? The file preview mechanism is already present on server.... In addition such two step approach would be more consistent with browser scenario and it is exactly what users do expect (“it works the same”).