there was a pen that used special paper to directly record your notes (15-20years ago)... should be possible nowadays to directly transfer this to a connected device and have it feed it to an llm.
and after looking it up, it appears they are still available: https://www.livescribe.com/landingpage/ls3_onenote/
That was likely what I was thinking of - I have vague memories of seeing an ad for this in Popular Mechanics or Popular Science in the 2000s.
They still exist, along with a bunch of different ones. I don't think it's going to be all that different compared to just writing notes in an e-book or on an iPad though. And for many people who learn in other ways, the iPad or similar is superior because you can copy in pictures, make diagrams, and use other ways of learning all in one spot. For me, honestly, something like OneNote (or especially Obsidian) is awesome, because it's super easy to tie in AI into mark down text.