Bookmarks have now been added to Epicyon.

So if you want to reply to a post, but not right now, or if it contains a link that you want to follow later then you can select the bookmark icon at the bottom of the post and it will be added to the top of the Saves timeline.

Why Saves rather than bookmarks? It's just a shorter word which fits more easily on the button.

In the present implementation bookmarks are only for private viewing by a single account, but in principle there's no reason why shared bookmarks couldn't exist. That might be added in future, but it's better to avoid complexity until it's demonstrated that it's really required.