Fantastic idea! I think the hardest part for people to adopt this will be overcoming atrophied handwriting skills and no autocorrect.

One thing that doesn't seem clear to me from reading without signing up is how do you actually upload content? Do you have to have paper and pen and then take a picture of it, or do you provide some kind of excalidraw-like canvas for writing? I notice there isn't any paper background or line rules, which I think would also be nice for those who fancy a bit of structure when reading/writing.