When I first tried Joplin, I also wanted to pour the notes from my OneNote in.
I didn't see a way to do it directly, so I imported from ON to Evernote, then from EN to Joplin.
That didn't work very well, mostly because EN tried to keep the layout and that totally broke when converted into markdown.
I didn't bother for a long time. Then I've simplified some of the worse layouts in ON and tried to repeat the process.
Then Evernote told me I need some old (2013, I think?) version of OneNote installed and that it won't work with the one from Windows Store - which seemed to be the only one easily available.
So, questions: Have any of you tried any of this recently?
Or some other way to import from ON?
I think I might try to dig up an older version of OneNote, install it into a VM and do the migration there... but then again, it might take as much time as just doing the migration manually.