

Nebo doesn't have all the features of OneNote, but it has some killer ones that have made it worthwhile for me. At the same time, Nebo supports exporting and notebooks into a variety of formats, including raw text files, word documents, and PDFs. I can't access the notebooks at but when I open Nebo on one device computer, I can readily retrieve changes I made on another. It's manual, but at least I can force syncing to happen. The sync is reliable, but I can identify some drawbacks.
EVERNOTE MAC STRIKETHROUGH SHORTCUT OFFLINE
Keeping multiple offline backups (monthly, say) should be much more straightforward with OneNote than Evernote, if you’re backing up in each programs native formats. If you ever need the VM, just copy the most recent version of your OneNote notebook files to it and you should be set. If you save a working VM with macOS (or Windows) and a local copy of OneNote and your files now, it should still be usable in 50 years, even if Microsoft itself is long gone by then.
EVERNOTE MAC STRIKETHROUGH SHORTCUT PLUS
On the plus side, OneNote files can work offline and easily be transferred between computers, whereas Evernote is more of a cached system. I’m not sure if shapes and drawings are stored as raster images or vector instructions. It should be technically possible to export to HTML, but formatting multiple overlapping text blocks and attachments might be an issue. RTF is probably a better fit than HTML for preserving formatting (extrapolating from how MS Word and Outlook behave). So, anything beyond a simple note is not at all as straightforward to export. Unlike Evernote, where each note is a single stream of ENML (basically HTML) with inline links to attachments and images, a single OneNote page can have many different text blocks, images, drawings, etc. There is a detailed specification documented at the Library of Congress (and at Microsoft’s site), so someone would be able to build a third-party reader at some point in the future without Microsoft’s help or permission. That’s also what makes export (except to another sort of database) quite a challenge. That’s how it can store change history, for example. pst/.ost files, I believe… ‘ESE’, aka ‘JET Blue’). The OneNote file format is actually based on a mature flat-file database (similar to that used for Active Directory and Outlook. That may the best bet for easily preserving formatting, but for large numbers of note pages, of course, it’s only really feasible with automation. From there, further export formats would be available. You could probably (manually) ‘select all’ inside of each note and then copy/paste into a MS Word document (which is now an open standard).

Your best bet is probably either some sort of scripting to extract the content while OneNote is running (I’m not sure if the Mac version has AppleScript support), or processing the raw file itself. The lack of export is a problem it unlikely to be fixed for technical reasons.
