I wrote something similar: https://github.com/maoserr/epublifier
It's more geared towards longer web novels with 50+ chapters (I've used it on novels with 500 chapters before). Instead of opening each page as a tab, it fetches chapters from a Table of Contents page.
It was written for jnovel/cnovel/knovel site, but it can handle any generic page that has a list of links.