Not self-hosted so I doesn’t really answer your question… However, if you’re still a student consider the switch to Zotero.
Things you can self-host though, to make your books available everywhere, is some webdav sever to link your books directly to zotero and access them on every device.
If you’re serious about book reading and study, nothing beats Zotero !
The solution here is to use a wireguard (or similar technology) server and use it on all your devices. People already use VPNs for everything, so adding this layer isn’t that much of a hassle !