I usr it every day its great.

Thats the idea! You just have to get them off the store and download them somehow.

Calibre is what I would take a look at. There is a web version that has a couple of different setups. for docker this looks interesting:

https://github.com/linuxserver/docker-calibre-web

Ive also used yunohost (mostly for ease of use and backups) here: https://apps.yunohost.org/app/calibreweb

Its basically the same thing either way.

am I right in understanding that I can host my library of ebooks on my home server then point a client at that server so I have access to my full library without having to save the books locally on device?

Some do this and some dont. I personally find ebooks to be so small that it doesnt matter, but some people use the server client to keep track of where they were at on certain books, helpwith their large collection, share with others of the family, etc…etc… And I think books with pictures such as manga, magazines, or other such take up more room so it might make sense if you have a lot of those.

I personally like having the system auto-update my device with new books and convert into nice to read formats for my custom devices. It works out really well.

calibre is pretty great. I also have a kobo and its the reason I can load/convert a lot of what I read.