With my Clara HD, I can upload with calibre but what I do more often is to convert epub to kobo specific one Kepubify. The reader can read regular epub but you don't have book progression, meta data etc the same as with the kepub.
Then put the result on a local web server (even possible on android if you're on the go).
I then use the built-in kobo web browser (in beta menu) to browse and download the book.
I've got a Kobo Libra2.
Pretty happy with the build quality and screen. Less happy with the walled garden approach that Kobo seem to be operating.
That'll probably be something I take into account when I come to get my next model.
With my Clara HD, I can upload with calibre but what I do more often is to convert epub to kobo specific one Kepubify. The reader can read regular epub but you don't have book progression, meta data etc the same as with the kepub.
Then put the result on a local web server (even possible on android if you're on the go). I then use the built-in kobo web browser (in beta menu) to browse and download the book.