I just tried feeding
Abbyy FineReader a native PDF followed by a bitmap PDF (ie. set of scanned pages, with an OCR layer on top) and save them as EPUB files: In both cases, it did an amazing job, with only a few wrong carriage returns.
Much nicer than open-source solutions like poppler or even mutool, that both require more tedious editing.
But then… the price isn't the same.