I would like to be able to share whatever book i'm reading (or just end reading) on stories in instagram the same way I can share a movie from letterboxd. Just the cover, author and book name in an image.

I haven't saw this feature in GR or any similar app, so there's a serious chance to have an impact being the first book dedicated app to be in those spaces.
This feature would also help to spread the app to a broader and mainstream audience, given the fact that instagram is the SSNN to share stuff by default this could bring new users, eyes, collaborators and even possible donors.
(attached a SS of how looks when you share a movie from letterboxd)