I second calibre-web. I installed it on an i3-cpu/8gb-ram thinkpad, and in the last couple of weeks give/take I’ve uploaded 180+gigs of books/articles/magazines I’ve collected over the last decade. Also if you want a simple solution for installation, then you might want to try freedombox; which is a Debian based NAS like solution that uses standard Debian packages. It has a ton of one button installs like: media-wiki, calibre-web, wordpress, syncthing, searx(pvt.search aggregator), mumble(audio-voice server), and more. Easiest way to setup calibre-web if you ask me. Also it should be pretty easy to dockerize it since it’s simply Debian. https://wiki.debian.org/FreedomBox
I don’t like CF tunnels, b/c I prefer to tunnel in w/ Tailscale-VPN, and Reverse proxy w/ Caddy; that way I will using my bandwidth alone, so I can stream unlimited locally saved/served media. CF tunnels are super non-specific about how much data they might consider too much. I just don’t want to risk it, plus w/ TS I get a free TS-domain. My budget is tiny!