I found these comments while searching the web for how to annotate epub files. I too would gladly pay to have this feature. Bring it on Xodo!
enable Epub format
Would gladly pay for this !
Since there is a multitude of epub and ebook files available, it would be nice to be able to read and do the same things, like annotate, highlight, comment, etc. as with PDF files.
I suggest that you design a update to read ebook and epub