If it uses tags correctly you can just filter in and out what you want to see, then bunch by other common tags or whatever.

I have not reached the point of finding the right book hosting to properly self host my large collection of books, so I can’t really give a suggestion for a good browsing experience, but just generally speaking tags allow as much structure and organization as the front end wants to take advantage of. I’ve seen plenty of platforms that, once you pick your first tag, give a sorted list of other common tags you can dig down into, in addition to showing the list of content that meets the tag by whatever criteria you have. (An example I’m not sure exists, but very easily could, is to take the highest frequency set of tags with the least overlap (fiction/nonfiction/kids) and display them as titled shelves, then, once you click that, breaks down that group in the same manner until extra tags aren’t really useful.)

But in terms of the information they contain, the real world is fuzzy, so a method that allows for fuzzy buckets instead of strict ones is going to be more representative of the eventual content.