In reply to Aaron Davis.

That's definitely a solid-sounding feature request to post in the issue queue.

It might also make a somewhat reasonable beginner pull request if you wanted to tackle something like in the code.

I'll note for doing this manually, one could add a database row in mySQL in the wp_postmeta table with the following values:
meta_key: mf2_read-status
meta_value: a:1:{i:0;s:7:"to-read";}

Adding this pair will cause Post Kinds to display the Read as the sub-type "Want to Read" in the resulting post. For the other two types you'd want to replace "to-read" with either "reading" or "finished". I've tried it out on a few prior posts and it seems to work pretty well.

I might recommend doing this in the admin UI using custom fields, but if I recall correctly, doing it that way will add some additional code that will prevent Post Kinds from finding and displaying it properly.