The following applies to PDFs that were created over the last decade or so, and it's based on converting a few hundred PDFs to ebook formats over that period.
Over that period Word and Wordperfect have both done a pretty good job of importing 'contemporaneous' PDFs that were exported from either and LO Writer. Word and I'm told by a couple of collaborators Wordperfect too, has improved over that period (i.e Word 2025 is better than Word 2012). I have not tried importing PDF's into a recent version of LO Writer but I'd be surprised if it wasn't the same.
Wordperfect can export an EPUB from an imported PDF. Word can save an imported PDF as DOCX… and probably LO Writer too. There are several ways to convert a DOCX to EPUB… my current preference is to import the DOCX into the calibre ebook-editor and save the EPUB from it.
I have an inkling the ebook-editor in the upcoming calibre release will support Kobo formats alongside the existing support for EPUB and AZW formats.
Added: Last week it took me about 15 minutes to convert a 200,000 word novel from PDF to EPUB. I then spent another 30 minutes in Word dealing with chapter and scene breaks.
BR