Okay, let's take stock of where we're at.
Sources of Content
books
articles
article series
video playlists
photo posts
Many, many video posts
Text updates
Okay, so the obvious way to get the content would be by reverse engineering the API. This basically means listening to the SSL traffic on the mobile app and figuring out what endpoints it's hitting and then retrieving the data directly from those endpoints and importing it into the Postgres database or some collective warehouse or repository.
https://docs.google.com/spreadsheets/d/1DgR4hnIYL3NzzkxqaymbZO-fZaDFKwS4ebKFCi0fHjk/edit?gid=1246962951#gid=1246962951