I would love to have some support for webp, since I am always running out of space on my Ipad Air (128g!) because of the comics I carry on it! More importantly, when/if - the feature does get introduced, I hope there's an option to convert all the comics already in your library to the webp format in order to quickly free up space. This would be immensely helpful since the way ComicZeal stores the comics doesn't make it easy to export them out again in order to carry out the conversion process.
In fact, even if ComicZeal doesn't introduce webp - I'd love for there to be an option to recompress library comics to some extent to minimize size. Doesn't have to be very customizable, but I should (hope) to be able to screen-native sizes, at least.