add_filter('woocommerce_variation_option_name', 'display_price_and_stock_status_in_variation_option_name');

function display_price_and_stock_status_in_variation_option_name($term)
{
    global $product;

    if (empty($term)) {
        return $term;
    }
    if (empty($product->get_id())) {
        return $term;
    }

    $variation_id = $product->get_children();

    foreach ($variation_id as $id) {
        $_product = new WC_Product_Variation($id);
        $variation_data = $_product->get_variation_attributes();
        $stock_status = $_product->get_stock_status();
        $stock_status = str_replace(array('instock', 'outofstock', 'onbackorder'), array('In Stock', 'Out of Stock', 'Pre-order'), $stock_status);

        foreach ($variation_data as $key => $data) {
            if ($data == $term) {
                $remaining_stock = $_product->get_stock_quantity();

                if ($remaining_stock > 2) {
                    $stock_status_text = 'In stock';
                } elseif ($remaining_stock == 2) {
                    $stock_status_text = 'Low in Stock';
                } elseif ($remaining_stock == 1) {
                    $stock_status_text = 'Only 1 left';
                } elseif ($remaining_stock == 0 && $_product->is_on_backorder()) {
                    $stock_status_text = 'Pre-order now';
                } else {
                    $stock_status_text = 'Sold Out';
                }

                $html = $term . ' (' . $stock_status_text . ')';
                return $html;
            }
        }
    }

    return $term;
}