Enable quantity field on shop page

// Remove the default add to cart button

remove_action( 'woocommerce_after_shop_loop_item', 'woocommerce_template_loop_add_to_cart', 10 );

// Add custom add to cart form for both simple and variable products

add_action( 'woocommerce_after_shop_loop_item', 'custom_add_to_cart_form_on_shop_page', 10 );

function custom_add_to_cart_form_on_shop_page() {

    global $product;

    if ( $product->is_type( 'simple' ) && $product->is_purchasable() && ! $product->is_sold_individually() ) {

        // Simple product add to cart with quantity

        echo '<form style="display:flex; justify-content:center; gap:8px;" class="cart" action="' . esc_url( $product->add_to_cart_url() ) . '" method="post" enctype="multipart/form-data">';

        woocommerce_quantity_input( array(

            'min_value' => $product->get_min_purchase_quantity(),

            'max_value' => $product->get_max_purchase_quantity(),

            'input_value' => 1,

        ), $product );

        echo '<button type="submit" name="add-to-cart" value="' . esc_attr( $product->get_id() ) . '" class="button alt">' . esc_html( $product->add_to_cart_text() ) . '</button>';

        echo '</form>';

    } elseif ( $product->is_type( 'variable' ) ) {

        // Variation form copied from single-product page template

        $attributes = $product->get_variation_attributes();

        $available_variations = $product->get_available_variations();

        if ( empty( $available_variations ) ) {

            echo '<p class="stock out-of-stock">' . esc_html__( 'This product is currently out of stock and unavailable.', 'woocommerce' ) . '</p>';

        } else {

            echo '<form class="variations_form cart" action="' . esc_url( get_permalink( $product->get_id() ) ) . '" method="post" enctype="multipart/form-data" data-product_id="' . esc_attr( $product->get_id() ) . '" data-product_variations="' . esc_attr( wp_json_encode( $available_variations ) ) . '">';

            echo '<table class="variations">';

            foreach ( $attributes as $attribute_name => $options ) {

                echo '<tr>';

                echo '<td class="label"><label for="' . esc_attr( sanitize_title( $attribute_name ) ) . '">' . wc_attribute_label( $attribute_name ) . '</label></td>';

                echo '<td class="value">';

                wc_dropdown_variation_attribute_options( array(

                    'options'   => $options,

                    'attribute' => $attribute_name,

                    'product'   => $product,

                ) );

                echo '</td></tr>';

            }

            echo '</table>';

            echo '<div class="single_variation_wrap">';

            /**

             * woocommerce_before_single_variation Hook.

             */

            do_action( 'woocommerce_before_single_variation' );

            /**

             * woocommerce_single_variation. Contains the selected variation price, stock info, etc.

             */

            do_action( 'woocommerce_single_variation' );

            /**

             * woocommerce_single_variation_add_to_cart_button hook.

             * Note: This will output quantity + submit button

             */

            do_action( 'woocommerce_single_variation_add_to_cart_button' );

			echo '<style>

            	form.variations_form.cart .woocommerce-variation-add-to-cart.variations_button {

					display:flex;

					justify-content:center;

					gap:8px;

				}

        	</style>';

            /**

             * woocommerce_after_single_variation Hook.

             */

            do_action( 'woocommerce_after_single_variation' );

            echo '</div>';

            echo '</form>';

        }

    }

}