https://pwmt.org/projects/zathura-pdf-mupdf/

The mupdf backend allows for reading PDF, epub, and some other filetypes. Currently it's not possible to configure the epub css in zathura, but it is supported by mupdf so it should be possible with a patch.

config

~/.config/zathura/zathurarc

books

~/.config/dprint/books.desktop

[Desktop Entry]
Version=1.0
Type=Application
Name=books
Comment=A minimalistic document viewer
Exec=books-fzf

#!/bin/sh
BOOKS="/home/kota/docs/books/"
SEARCH=$(fd . --type f "$BOOKS" -e pdf -e epub -x basename |\
	sort -R | dmenu -i -l 8)
SELECTION=$(fd "$SEARCH" "$BOOKS")
zathura "$SELECTION"