How to display the Gravity Perks Nested Forms table in PDFs?

You can output the Gravity Wiz Nested Forms field in Core and Universal PDF templates as a table using the following snippet:

add_action( 'after_setup_theme', function() {
    if ( class_exists( '\GFPDF\Helper\Fields\Field_Form' ) ) {
        class Field_Form_Original extends \GFPDF\Helper\Fields\Field_Form {
            public function html( $value = '', $label = true ) {
            add_filter( 'gpnf_template_args', function( $args ) {
                    $args['template'] = 'nested-entries-detail-simple';
                    return $args;
                } );

                $html = GFCommon::get_lead_field_display( $this->field, $this->get_value(), $this->entry['currency'] );
                $html = apply_filters( 'gform_entry_field_value', $html, $this->field, $this->entry, $this->form );

                $html = str_replace( '<th ', '<th align="left" ', $html );

                return \GFPDF\Helper\Helper_Abstract_Fields::html( $html );
            }
        }

        add_filter( 'gfpdf_field_class_form', function( $class, $field, $entry ) {
            return new Field_Form_Original( $field, $entry, GPDFAPI::get_form_class(), GPDFAPI::get_misc_class() );
        }, 10, 3 );
    }
} );

The table columns used are those selected in the Summary Fields setting for the Nested Form field in the Form Editor. Place the snippet in your active theme's functions.php file (or a similar location).