An item you can click your notes into that when you use the unique power on, opens up board of notes similar to what the furniture system does. This way you can make books and organize them into topics instead of trying to cram everything into a single note.
I think this would be amazing, personally.
Like a blank book perhaps? Then as you said, functions as a bulletin board in your inventory, that can be written in 'chapters' of sorts. Then, you can rename the 'bulletin board' book in your inventory to organize notes. I'd be a huge fan of this.
Yes, in RP sense a book, but functionally just an item that lets you absorb notes that mechanically functions like a furniture board item.