Library Journal created SELF-e, a program that curates/selects independently published books and puts them into the ebook lending collections of participating libraries. The author does not get paid, however. You must own the rights and be willing to donate the ebook.
This might be a good strategy for authors with more than one book, as a way to find readers, to introduce a series, or to get credibility. Books submitted to SELF-e may also be considered for certain awards and promotional opportunities.
To learn more about SELF-e: https://selfe.librariescreate.com/self-e/