Since Pressbooks is build on WordPress multisite with some modifications, looks like you can easily run this software to publish your own ebooks. Here are the installation instructions:
Upon further research, it looks like some of the server dependencies to export the book to other formats are not supported on default Reclaim Hosting servers (my web host):
However, if the system admin wants them, they can be added to a Reclaim Hosting dedicated server:
To be clear: we don't install server-level dependencies like that on shared hosting (really wish they could develop it to not require that), however since DoOO are dedicated servers if the admin of that system wants them we can install them.
— Reclaim Hosting (@ReclaimHosting) March 8, 2018
In other words, it looks like I could get it running, but it wouldn’t have all the features available unless I worked with my University’s DoOO server admin.