ultrabiker

Thank you @amimulihsanmahdi

I have created a function that will do what I would like.
For others to use as they would see fit.

// Create a custom shortcode to handle dynamic form embedding
// USE: [dynamic_fluentform id="11" ebook="my-ebook-slug"]
function dynamic_fluentform_shortcode($atts) {
    // Extract attributes passed to the shortcode
    $atts = shortcode_atts(array(
        'id' => '',         // FluentForm ID
        'ebook' => ''       // The dynamic eBook value or any custom param
    ), $atts, 'dynamic_fluentform');

    // Sanitize values (always sanitize user inputs/attributes)
    $form_id = intval($atts['id']);
    $ebook_id = sanitize_text_field($atts['ebook']);

    // Generate the FluentForm shortcode with dynamic hidden field value
    $output = do_shortcode('[fluentform id="' . $form_id . '"]');
    
    // Inject the hidden field value into the form using JS if necessary
    $output .= "<script>
        document.addEventListener('DOMContentLoaded', function() {
            var ebookField = document.querySelector('input[name=\"ebook_id\"]');
            if(ebookField) {
                ebookField.value = '" . esc_js($ebook_id) . "';
            }
        });
    </script>";

    return $output;
}

// Register the custom shortcode
add_shortcode('dynamic_fluentform', 'dynamic_fluentform_shortcode');