The Internet Archive has a "lending library" of post-1923 books where we own a physical copy, stored in a shipping container in a warehouse, and loan one digital copy at a time for each physical one that we own.

https://blog.archive.org/2010/06/28/digital-lending-library/

https://archive.org/details/lendinglibrary&tab=about

We're hoping to get libraries to join with us to make their books in remote storage available in a similar fashion.