I use Kavita to host ebooks and manga for myself. It's still work in progress, so do expect changes, though I haven't had huge issues on the stable releases so far. Besides Tachiyomi for comics/manga there aren't any native reading apps yet, so you will have to use the webinterface for the time being.

Another option often mentioned is Calibre Web, though I haven't used that myself.

Caliber is great, but if you have audiobooks, auidiobookshelf has gotten pretty decent at hosting ebooks too

Check out the docker version of calibre if you're into that https://hub.docker.com/r/linuxserver/calibre-web

Audiobookshelf is quite nice too. The ebook reader isn't quite there yet, but it develops very fast. Also apps for Android and iOS

I use Komga (https://github.com/gotson/komga) and it's pretty cool

Calibre is great but it’s not a server based program, it’s just a desktop client. There is Calibre-web which you can host which kinda turns it into a server but it does that by exposing a website you connect to that shows you the Calibre interface via VNC, so it’s a bit hackey.

I haven’t tried it but https://www.kavitareader.com/ might be a good alternative if you end up not liking Calibre.

I've been playing with Audiobookshelf and it does do books as well.

Take a look at Calibre-Web (github.com/janeczku/calibre-we…) which I've been using for what you ask for quite a while now. As the name suggests it can also take advantage of a pre-existing Calibre eBook Database.