inspiration:
perishablepress.com/better-default-directory-views-with-htaccess/

apache-conf:

IndexOptions SuppressHTMLPreamble FancyIndexing
HeaderName /dirlist-header.html

shell vscode remote:

code /etc/apache2/sites-enabled/000-default-le-ssl.conf
apachectl restart

php (disabled):
[php $dir = explode('?', $_SERVER['REQUEST_URI'])[0]; ]
[= $dir ]
/dirlist-header.html contents: [[
<?php $dir = explode('?', $_SERVER['REQUEST_URI'])[0]; ?><!DOCTYPE html>
<html lang="en">
<head>
<title><?= $dir ?> dir-list</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="/sitewide.css">
</head>
<body>
<h1><?= $dir ?> dir-list</h1>
]]