Virtual pages from static HTML files (or something like that)

I have a few pages that aren’t content managed but static HTML, which need to be integrated into a Kirby-managed site. I imagine that I have these HTML documents in a directory (e. g. inside a Kirby page’s directory or some other subdirectory) and the CMS should magically list these and/or add them to the navigation (or referenced in any other way, using Kirby’s URL structure). What’s the best way approach to this?
I found the article about merging content sources but I’m not proficient enough with PHP and model stuff to understand what to do.

Or can they be managed with the files field somehow?

HTML files cannot be uploaded as files. What you could do is create a standard page folder for each of those pages, then in the text file for each page reference the name of the html file, then in the template, read those html files.

/content
  test/
  test.txt

Test.txt

Title: Test

----
Htmlfile: test.html

/site/templates/test.php

<?php 
echo F::read($kirby->root('index'). '/'. $page->htmlfile()); //or wherever you want to put those files

Thanks, interesting approach.
However, what’s the difference (or rather advantage) of F::read() to just doing a simple PHP include/require?

It probably doesn’t matter for small files. Just a habit.

Thanks much.