Looking for WordPress PDF Converter with Custom Templates?

You could create a new endpoint using add_rewrite_endpoint, for example /datasheet/ so your URL would be example.com/product/datasheet.

You can then hook in to template_redirect and check that you are on a product page with this datasheet query var set.

From here, you can then load a separate template which will display the fields you require (and exclude those ACF fields you mention you don’t want to display). You can then use PHP’s output buffer functions to copy your template into a string, and pass that to a PFP tool such as dompdf.

if (isset($wp_query->query_vars['datasheet']) && is_singular('product')) {
   global $post;

   ob_start();
   include(locate_template('template-parts/product/datasheet.php'));
   $datasheet = ob_get_contents();
   ob_end_clean();

   $dompdf = new Dompdf();
   $dompdf->loadHtml($datasheet);
   $dompdf->stream($post->post_name . '.pdf');

   exit();
}

This is a simplified version of code we use to provide a product datasheet, but should give you something to think about.