I think Calibre advocates forgot what it's like to setup it for the first time and what a messy ugly process it is for new timers. A containerized version needs VNC access to set it up and perform some un-intuitive UI actions https://docs.linuxserver.io/images/docker-calibre/#applicati...

I've used https://www.kavitareader.com/ but it's not perfect either, this space could be "disrupted" by a Plex like product with opensource + licensed offerings but the target market is pretty small I think.