The add-on looks and controls great. I had two problems with it:

⦁ It doesn't hyphenate words, which, with justified texts, leaves wide gaps. I know that the problem may be not with the add-on but with the document's CSS not including hyphenation preset. On my desktop and smartphone readers text is hyphenated, so I guess it depends on the reader apps too.🤷🏻‍♂️

⦁ It failed to load images. It may be because the images are vector (.svg). If I click on them and hit "Open image in a new tab", the image loads. I haven't tried replacing .svg's with raster images, but I assume the add-on has no problems with them.