You can download images (as long as they haven't been inserted dynamically) by turning on the option Allow image manipulation in Configuration. Then you will be - able to right-click an image and save it to disk or open it in a new tab (only tested in Wikimedia ZIMs). However, this doesn't work in the UWP app: instead, you can enable - the Insert breakout link option, export the article to a new browser tab (by clicking the Breakout link), and then you will be able to manipulate images in the browser tab. - Please note that enabling Image manipulation or the Breakout link feature can interfere badly with some ZIMs that rely heavily on active content. So turn these options off if you are - using such ZIMs. + able to right-click an image and save it to disk or open it in a new tab (only tested in Wikimedia ZIMs). However, this doesn't work in the UWP or NWJS apps. Workaround + for the UWP app: you can enable the Insert breakout link option, export the article to a new browser tab (by clicking the Breakout link), and then you will be able to manipulate + images in the browser tab. Please note that enabling Image manipulation or the Breakout link feature can interfere badly with some ZIMs that rely heavily on active content. So turn + these options off if you are using such ZIMs.
You can download EPUBs and PDFs, e.g. from Gutenberg ZIMs, in JQuery mode, but the proprietary User Interface doesn't work (use title search instead). In the UWP Desktop app