I wonder what would happen if: if I post 2 pieces of content, my friend would have to comment on the first one to see the next one.

I suppose the app will then mostly be full of throwaway comments in the form of "Cool" or "Wow". But maybe add a modifier that if the poster doesn't have any meaningful reply to a commenter's (let's name him Elon) comment, then the poster's next content will not be shared with Elon next time.