My thoughts for a mobile app for the Wikisources is something that allows for a search in the language of interest then pulls a dynamic download of an epub version of the work from https://wsexport.wmflabs.org/tool/book.php
I was thinking something simple
- language choice
- api search in the main namespace
- select work to output (whole work or subpage of work) and generate epub
I wasn't thinking that any mobile app would do editing as at this stage it is not something easy to do on a smaller mobile app, and bigger movile devices can use inbuilt browsers.