Wikisource has an OPDS (Open Publication Distribution System) catalog, which provides a way to directly download readable works from Wikisource.
The catalog is regenerated on a daily basis.
Adding the catalog to your device
The URL is:
Add this to your device's list of OPDS catalogs.
The catalog is provided by the WS Export tool. Bugs and feature requests can be filed at the Phabricator project.