I've been looking for something for my RPG pdf collection and haven't really found anything that scratches every need I have for it yet. I've gone through most of what's out there and didn't really see many great options. I mostly want to organize/categorize my collection of ttrpg e-books (reading I can do through dropbox as I don't really jump from one item to another often enough to justify syncing my entire 100k+ collection), so I just settled on Zotero. It's mainly meant for journals and scholarly works, but it seems like it fits part of my use-case and it's tagging features are decent enough. Syncing PDFs is an option, but I'd have to get into the paid tier to have my whole collection accounted for.

Jellyfin I guess does have support for ebooks through a plug-in, but it isn't terribly great IMO and you'll still need something else like Tailscale I believe to actually be able to view stuff outside of your home wifi network. There's some other options out there I believe, though they all seemed to be geared towards Manga collections, so if you're looking to organize through this system, those may not work as well either (and you still may need Tailscale regardless).