I would use the completely rewritten TOC described at: TOC-macros Rewritten (+ a lot of new fuctionality) - Part 2
Then I would use a structure similar to this one
toc-for-multiple-topics.json (1.8 KB) and import it to the preview edition: https://tiddlywiki5-git-fork-pmario-toc-v53x-10443d-jermolenes-projects.vercel.app/
to get this:
With the new TOC macros there will be many other ways to structure a TOC based on tags, fields and a mixture thereof.
The tiddlers attached here will be part of the preview soon, once it is built by the Vercel bot.
have fun!
Mario