Bookworm reminds me of Polar-Bookshelf [1]. They do not seem to have exactly the same features and use-cases, but I think it might be worth comparing (only tried Polar so far).
Right now I'm working on making Polar easier to use. I think initial users get confused and I'm trying to fix that.
Additionally we're working on a web version but I think that's 1-2 weeks away.
You can use Calibre to convert the ePub to PDF and then import.
ePub is used a lot more than I would have thought.
Initially we might just convert the ePub to PDF.