Earlier quoted context omitted.
I use a Boox E-Ink tablet with the built-in handwriting notes app. It exports to PDF and I can copy everything to my Debian machine via ADB. I absolutely love it. E-Ink is close enough to paper for me, and the EMR (Wacom) stylus is close enough to a pen for me.
Yeah but do you trust those guys?
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.