for now, i found the best thing to be to use two tools:
- in-built one note importer works well to get almost all data. It is just overly complex markdown if later i want to edit it.
- I also use onenote to joplin markdown converter (ref: OneNote export to Joplin) it works well but has many imitations
So i have two imported notebooks: markdown one and a "joplin" one and am manually checking each page and tidying up the import. Of course not perfect but at least I have a good solution and am able to move away from Microsoft 