Hope the following code will help.
shipping step:

payment step:

Create a CMS block from Magento Admin called 'checkout_help' (identifier)
Vendor/Module/Model/CheckoutCmsBlocksConfigProvider.php
<?php
namespace Vendor\Module\Model;
use Magento\Checkout\Model\ConfigProviderInterface;
use Magento\Cms\Block\Block;
use Magento\Framework\View\LayoutInterface;
class CheckoutCmsBlocksConfigProvider implements ConfigProviderInterface
{
/**
* @var LayoutInterface
*/
private $layout;
/**
* @param LayoutInterface $layout
* @param array $data
*/
public function __construct(
LayoutInterface $layout,
array $data = []
) {
$this->layout = $layout;
}
/**
* @return array
*/
public function getConfig(): array
{
// 'checkout_help' is the CMS block identifier
return [
'checkout_help_cms_block_content' => $this->getBlockContent('checkout_help')
];
}
/**
* @param string $blockIdentifier
* @return string
*/
private function getBlockContent(string $blockIdentifier): string
{
return $this->layout
->createBlock(Block::class)
->setBlockId($blockIdentifier)
->toHtml();
}
}
Vendor/Module/etc/frontend/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\Checkout\Model\CompositeConfigProvider">
<arguments>
<argument name="configProviders" xsi:type="array">
<item name="checkout_cms_blocks_config_provider" xsi:type="object">Vendor\Module\Model\CheckoutCmsBlocksConfigProvider</item>
</argument>
</arguments>
</type>
</config>
Vendor/Module/view/frontend/layout/checkout_index_index.xml
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceBlock name="checkout.root">
<arguments>
<argument name="jsLayout" xsi:type="array">
<item name="components" xsi:type="array">
<item name="checkout" xsi:type="array">
<item name="children" xsi:type="array">
<item name="sidebar" xsi:type="array">
<item name="children" xsi:type="array">
<item name="sidebarAfter" xsi:type="array">
<item name="component" xsi:type="string">uiComponent</item>
<item name="displayArea" xsi:type="string">sidebar-after</item>
<item name="children" xsi:type="array">
<item name="need-help-block" xsi:type="array">
<item name="component" xsi:type="string">Vendor_Module/js/view/need-help</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</argument>
</arguments>
</referenceBlock>
</body>
</page>
Vendor/Module/view/frontend/requirejs-config.js
var config = {
map: {
'*': {
'Magento_Checkout/template/sidebar.html': 'Vendor_Module/template/sidebar.html'
}
},
config: {
mixins: {
'Magento_Checkout/js/view/sidebar': {
'Vendor_Module/js/view/sidebar-mixin': true
}
}
}
};
Vendor/Module/view/frontend/web/js/view/sidebar-mixin.js
define([
'ko',
'Magento_Checkout/js/model/step-navigator',
], function(ko, stepNavigator) {
'use strict';
return function(sidebar) {
return sidebar.extend({
visible: ko.computed(function () {
return stepNavigator.steps()[stepNavigator.getActiveItemIndex()] && stepNavigator.steps()[stepNavigator.getActiveItemIndex()].code !== 'welcome';
}),
visibleOnMobile: ko.observable(false),
});
};
});
Vendor/Module/view/frontend/web/template/sidebar.html
<aside class="opc-sidebar opc-summary-wrapper" data-bind="visible: visible">
<div class="sidebar-content inner-wrapper-sticky">
<div id="opc-sidebar">
<!-- ko foreach: getRegion('summary') -->
<!-- ko template: getTemplate() --><!-- /ko -->
<!--/ko-->
<div class="opc-block-shipping-information">
<!-- ko foreach: getRegion('shipping-information') -->
<!-- ko template: getTemplate() --><!-- /ko -->
<!--/ko-->
</div>
</div>
<div class="opc-sidebar-after">
<!-- ko foreach: getRegion('sidebar-after') -->
<!-- ko template: getTemplate() --><!-- /ko -->
<!--/ko-->
</div>
</div>
</aside>
Vendor/Module/view/frontend/web/js/view/need-help.js
define([
'uiComponent',
'mage/url'
], function(Component, urlBuilder) {
'use strict';
return Component.extend({
defaults: {
template: 'Vendor_Module/need-help'
},
helpMessage: window.checkoutConfig.checkout_help_cms_block_content
});
});
Vendor/Module/view/frontend/web/template/need-help.html
<if args="helpMessage">
<div class="help-block">
<div class="title" data-role="title" data-bind="i18n: 'Below Summary Content'"></div>
<div class="content" data-role="content" data-bind="html: helpMessage"></div>
</div>
</if>