As another poster mentioned about the ReMarkable, the Boox works just fine offline. I do use mine online, e.g. for reading HN as I prefer the E-Ink screen for text. But as for note-taking, everything I do is offline, including moving the PDF documents to the desktop via ADB.
My solution was:
- Take notes on paper
- Scan with Genius Scan (free) or similar
- Upload to Microsoft Document Intelligence on Azure to get character recognition and a PDF output (standard OCR sucks for handwriting; also free for up to like 50 docs a month)
- Tidy up the text and store in Mediawiki long-term (you can also upload a copy of the OCR enabled PDF) (FOSS)
- File paper notes
- Throw paper notes once module is complete