generate a static copy of the website footer html

I managed to do it like this:

define('WP_USE_THEMES', true);
require( '../wp-load.php' );
// Register all scripts and styles
do_action('wp_enqueue_scripts');

// Execute footer hooks
do_action('get_footer');

// output the js
wp_print_footer_scripts();
wp_footer();

It also outputted the enqueued CSS files, so I tweaked it by making a helper function

function dequeue_scripts_or_styles($slug) {
    wp_dequeue_style( $slug );
    wp_deregister_style( $slug );
}

So the final code is

define('WP_USE_THEMES', true);
require( '../wp-load.php' );
// Register all scripts and styles
do_action('wp_enqueue_scripts');

// Remove things that should not sit in the footer
dequeue_scripts_or_styles( 'wc-responsive-video-scripts' );
dequeue_scripts_or_styles( 'sage/css' );


// Execute footer hooks
do_action('get_footer');

// output the js
wp_print_footer_scripts();
wp_footer();
?>
     </body>
 </html>