Magento – magento 2.3 when Product export gets “Message is added to queue, wait to get your file soon

To add SKUs Column in order Ui grid. You need to modify below files.

TO add column, add below code in your module

[vendor]/[module]/view/adminhtml/ui_component/sales_order_grid.xml

<?xml version="1.0" encoding="UTF-8"?>
    <listing xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <columns name="sales_order_columns">
        <column name="skus">
            <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="sortable" xsi:type="boolean">false</item>
                    <item name="visible" xsi:type="boolean">true</item>
                    <item name="label" xsi:type="string" translate="true">Skus</item>
                </item>
            </argument>
        </column>
    </columns>
</listing>

[vendor]/[module]/etc/adminhtml/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Sales\Model\ResourceModel\Order\Grid\Collection">
        <plugin name="ordercolumn_grid_load_before" type="[vendor]\[module]\Plugin\Admin\Order\Grid" sortOrder="10" disabled="false"/>
    </type>
</config>

and then Create a plugin file.

[vendor]/[module]/Plugin/Admin/Order/Grid.php

<?php
namespace [vendor]\[module]\Plugin\Admin\Order;

use Magento\Backend\Model\Auth\Session;
use Magento\Framework\App\ResourceConnection;
use Magento\Framework\Data\Collection\EntityFactoryInterface;
use Magento\Sales\Model\ResourceModel\Order\Grid\Collection;
use Magento\User\Model\ResourceModel\User\Collection as UserCollection;

class Grid extends \Magento\Framework\Data\Collection
{
    protected $coreResource;

    protected $adminUsers;

    public function __construct(
        EntityFactoryInterface $entityFactory,
        ResourceConnection $coreResource,
        UserCollection $adminUsers
    ) {
        parent::__construct($entityFactory);
        $this->coreResource = $coreResource;
        $this->adminUsers = $adminUsers;
    }

    public function beforeLoad($printQuery = false, $logQuery = false)
    {
        if ($printQuery instanceof Collection) {
            $collection = $printQuery;

            $joined_tables = array_keys(
                $collection->getSelect()->getPart('from')
            );

                $collection->getSelect()
                    ->columns(
                        array(
                            'skus' => new \Zend_Db_Expr('(SELECT GROUP_CONCAT(`sku` SEPARATOR " & ") FROM `sales_order_item` WHERE `sales_order_item`.`order_id` = main_table.`entity_id` GROUP BY `sales_order_item`.`order_id`)')
                        )
                    );

        }
    }
}

You have to run cron by command line as mentioned here: php bin/magento cron:run

https://github.com/magento/magento2/issues/23450#issuecomment-507581035

Then refresh the export page and you should see the file at the bottom.