Using Direct2Digital as my aggregator for publishing has many advantages. One that I really like is their addition of making your book available to Overdrive (and their newer app Libby). The only drawback is that librarians need to be made aware of your publication. And they make such decisions through requests that they receive from the library cardholders.
Requests can be made through the Overdrive app itself, but not currently through the Libby app.
Watch This Space 