pflonk

This plugin allows you to pass content to any sidebar from the page without using userdefined fields. Therefore it is possible to use the WYSIWIG-editor of your choice.
How it works: 
This plugin comes with a new enclosing shortcode [sidebar_content][/sidebar_content] where you can place any content, you want to have displayed in the sidebar. You will be able to use other shortcodes within this shortcode to use galleries, videos or any other stuff in the sidebar of your choice.
Additionally there will be a new widget which you can insert into the sidebar you want to have the content displayed. 
If you would like to pass content to an existing sidebar, there is another possibility using the [insert_sidebar_content] shortcode in any place you want. You are able to pass an id and/or a class to that content, to be able to style it with css as you like. This happens by simply adding: 
[insert_sidebar_content id=”yourID” class=”yourClass”] to the shortcode. You can of course use just one or none of them. If you do not specify any custom class or id, there will be a standard class and id called “insert_scfs” applied to the content, wrapped in a div.
<h3>Features</h3>
<ol>
<li>Widget</li>
</ol>
<ul>
<li>optional title (if empty, no tag will be generated)</li>
<li>optional title tag (default h3)</li>
<li>optional title tag CSS-classes</li>
<li>optional content-wrapper tag (default div)</li>
<li>optional CSS-classes for content-wrapper tag</li>
<li>optional CSS-id for content-wrapper tag</li>
<li>default values for every of the above possibilities</li>
</ul>
<ol>
<li>Shortcodes</li>
</ol>
2.1 Content-Enclosement
<ul>
<li>[sidebar_content]CONTENT[/sidebar_content] for use on any page</li>
</ul>
2.2 Widget-Display
<ul>
<li>[insert_sidebar_content id=”yourID” class=”yourClass”] to display the content from the [sidebar_content]-Shortcode in any widget you like</li>
<li>applicable id and classes</li>
</ul>
You will find further support on http://dev.offensichtlich.net
<h3>Thanks</h3>
Thanks to the authors that provided information about how to implement this simple little function that I just put together:
Ryan Bosinger 
http://www.ryanbosinger.com/boztown/2013/03/07/wordpress-custom-content/
1st-tec.de 
http://www.tipps.1st-tec.de/wordpress/39-wordpress/sidebar-widgets/152-eigene-widgets-fuer-die-sidebar-erstellen.html

Sidebar-Content from Shortcode

This Plugin enables passing content to any sidebar from the page without using userdefined fields. Therefore it is possible to use the WYSIWIG-editor  …

toddhalfpenny

The easiest, and highest rated way to Add Widgets to Posts and/or Pages. Create unlimited dynamic sidebars (widget areas) and insert these into a WordPress post or page.
Create as many widget areas (Turbo Sidebars) from the settings menu, and these can be used multiple times.
Each sidebar can be called independently by a shortcode, and you can call more than one per post/page.
Sidebars can be included in the post/page by using a shortcode like the following, where <code>x</code> is the name of the sidebar.
<pre><code>[widgets_on_pages id=x]
</code></pre>
<blockquote>
With the <a href="https://datamad.co.uk/wordpress-plugins/widgets-on-pages/" rel="nofollow ugc">PRO</a> version the widgets can be inserted simply with clicks-not-code using a wizard in the visual editor. This version also includes layout options to easily set the widgets in columns/grid presentation.
Pro version also supports the configurable option to automatically add widgets to all your posts and/or pages. Choose the layout options and whether to add the sidebar and widgets before or after the content. Ideal for adding lists of related posts to the end of every post. Each post and page can also be individually excluded from the auto-inclsion of the widgets.
<a href="https://datamad.co.uk/wordpress-plugins/widgets-on-pages/" rel="nofollow ugc">Pro version</a> key features 
 * Responsive Horizontal/Column/Grid layout 
 * Auto insert in Header, Content, or Footer 
 * Priority Support
</blockquote>
Basic In-Content Instructions
<ul>
<li>Create a Turbo Sidebar, these are your special widget containers</li>
<li>Add widgets to the Turbo Sidebar in the same way as you do for normal sidebars</li>
<li>If using the visual editor use the Add Turbo Sidebar button to add the Shortcode into your post or page where you’d like it to appear.</li>
</ul>
The sidebars can also be added to any theme, using template tags. This is an ace way to add widgets/sidebars to a theme’s header and footer (or any other part of a theme).
Demo Video
<iframe loading="lazy" title="Adding Widgets to WordPress Posts and Pages" width="750" height="563" src="https://www.youtube.com/embed/w2LfCihCqRI?feature=oembed" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
Current Features Include
<ul>
<li>Highest Rating – 122 5* Reviews</li>
<li>No Coding needed</li>
<li>Create unlimited sidebars</li>
<li>Place them in posts/pages/custom post types</li>
<li>Add to themes using template tags</li>
<li>Works with ALL widgets and themes (let us know if you have an issue)</li>
</ul>
Recent Reviews
∗ ∗ ∗ ∗ ∗ Just purchased PRO version and well worth the money. – <a href="https://wordpress.org/support/topic/extremely-useful-plugin-19/" rel="ugc">@artmuns</a>
∗ ∗ ∗ ∗ ∗ Works as advertised + timely response to support request – <a href="https://wordpress.org/support/topic/works-as-advertised-timely-response-to-support-request/" rel="ugc">@3cstudio</a>
∗ ∗ ∗ ∗ ∗ Saving me HOURS of work – <a href="https://wordpress.org/support/topic/saving-me-hours-of-work/" rel="ugc">@andynick</a>

Widgets on Pages

The easiest and highest rated way to Add Widgets or Sidebars to Posts and Pages using Visual editor,  shortcodes or template tags.

Sidebar-Content from Shortcode vs Widgets on Pages