Even if you want it for just books, there are benefits to installing things like KOReader (way better ebook reader than the default). This allows you to sync with Calibre, etc.

Years ago, it was practically a hobby of mine to go to my local Goodwill, and find an extremely cheap old used Kobo and find someone to donate it to. Now I'm thinking of getting old Kobos just for the eink display so I can run simple apps on it - while continuing to use my regular Kobo as an ereader.