Add block after sidebar on checkout page

Question

For accesibility reasons I want to move checkout button after the sidebar. I am able to move checkout button to sidebar but I want to move it after the sidebar in the html layout. I am able to add blocks to #checkout container but it always appears before the sidebar even if I place it in web/js/template/sidebar.html after the sidebar div.

<div id="checkout" class="checkout-container">
........
........

<!-- my div appears here -->

<aside class="modal-custom opc-sidebar opc-summary-wrapper custom-slide">

</aside>

<!-- I want to add div here -->

</div>

Edit 1:

Following is what I tried. It adds a div before aside but not after aside.

onepage.phtml

<script type="text/javascript">
        var my_cms_block = 'Hello world';
</script>

sidebar.html

<div id="opc-sidebar" ...>...</div>
<div class="opc-help-cms" data-bind="html:my_cms_block"></div>

Edit 2

I tried to extend the checkout module and used sortOrder attribute but still my block loads before aside in html.

checkout_index_index.xml

<item name="sidebar" xsi:type="array">
    <item name="sortOrder" xsi:type="string">900</item>
</item>
<item name="afterSidebar" xsi:type="array">
    <item name="sortOrder" xsi:type="string">9999999999</item>
    <item name="component" xsi:type="string">MyModule_helper/js/summary/sidebar/buttons</item>
    <item name="displayArea" xsi:type="string">afterSidebar</item>
    <item name="config" xsi:type="array">
        <item name="template" xsi:type="string">MyModule_helper/summary/sidebar/buttons</item>
    </item>
</item>

onepage.html

<div class="afterSidebar">
    <!-- ko foreach: getRegion('afterSidebar') -->
    <!-- ko template: getTemplate() --><!-- /ko -->
    <!--/ko-->
</div>

Thanks in advance..

Answer 1

di.xml App/code/Vendor/Module/etc/frontend

<?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="Vendor\Module\Model\ConfigProvider">
       <arguments>
           <argument name="blockId" xsi:type="string">block_identifier</argument>
       </arguments>
   </type>
</config>

CmsConfigProvider.php

namespace Vendor\Module\Model;

use Magento\Checkout\Model\ConfigProviderInterface;
use Magento\Framework\View\LayoutInterface;

class ConfigProvider implements ConfigProviderInterface
{
   /** @var LayoutInterface  */
   protected $_layout;
   protected $cmsBlock;

   public function __construct(LayoutInterface $layout, $blockId)
   {
       $this->_layout = $layout;
       $this->cmsBlock = $this->constructBlock($blockId);
   }

   public function constructBlock($blockId){
       $block = $this->_layout->createBlock('Magento\Cms\Block\Block')
           ->setBlockId($blockId)->toHtml();
       return $block;
   }

   public function getConfig()
   {
       return [
           'cms_block' => $this->cmsBlock
       ];
   }
}

sidebar.html

   <div class="opc-block-shipping-information">
    <div data-bind="html: window.checkoutConfig.cms_block"></div>
   </div>