PS Touch projects are self-contained (as PS Touch's native PSDX format); they don't become, for example, JPEGs until you go to export.
There isn't a choice to export as PDFs but there are other choices like PSDX and PSD.
The desired export location will determine what file format you can choose to export as. e.g., Locally on your tablet, it'll be JPEG or PNG. Using Creative Cloud, that choice expands to PSDX (which will essentially create a backup of your project in the cloud and for use in other applications like desktop Photoshop). Using the "share" command expands the choices to PSD. (e.g., Sharing to your Dropbox account.)