Vladimir Prelovac

WP Wall is a “Wall” widget that appears in your blog’s sidebar acting as a cool shoutbox for your visitors.
The comment will appear in the sidebar immediately, without reloading the page.
All comments are internally handled by WordPress so that means you have normal comment moderation, SPAM protection and new comment notification.
WP Wall is fully customizable with a CSS file and included graphics.
WP Wall features: 
* Global commenting “Wall” 
* Comments are handled entirely by WordPress 
* RSS Feed for the Wall 
* Smilies 
* Instant delete for admin 
* Option to display HTML and make links clickable 
* Navigation through pages 
* Interactive Wall: It can automatically refresh turning into a chat
Plugin by Vladimir Prelovac. Also check out <a href="https://managewp.com" rel="nofollow ugc">ManageWP</a>.
<h3>License</h3>
This file is part of WP Wall.
WP Wall is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
WP Wall is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with WP Wall. If not, see <a href="http://www.gnu.org/licenses/" rel="nofollow ugc">http://www.gnu.org/licenses/</a>.

WP Wall

"Wall" widget that appears in your blog's sidebar acting as a cool shoutbox for your visitors.

Miguel Useche

This plugin provides a widget and a filter to display a collapsible list of categories in your sidebar or posts by using vanilla Javascript.
<h4>Features</h4>
<ol>
<li>Support for Gutenberg blocks. Add it to any FSE theme or Gutenberg compatible theme.</li>
<li>Display a collapsed list of your archives to reduce space.</li>
<li>Uses vanilla JS to add effects and to be compatible with all browsers.</li>
<li>Select the symbol for expanding/collapsing categories</li>
<li>Select categories to exclude, so it shows only the categories you want.</li>
<li>Autoexpand selected category (including it parent or child).</li>
<li>Support for multiple instances.</li>
<li>Simple layout configuration</li>
<li>Shortcode support [JsCategoriesList]</li>
<li>Translated to Spanish, Italian Russian, Slovak, Czech.</li>
<li>Compatible with most JS cache and minify plugins.</li>
<li>And more to come…</li>
</ol>
<h3>Configuration</h3>
<ul>
<li>Title: title of the widget.</li>
<li>Trigger Symbol: characters to be displayed as a bullet.</li>
<li>Symbol position: where to put the expand/collapse symbol.</li>
<li>Effect: JS’s effect to use.</li>
<li>Order by: display order of categories.</li>
<li>Expand: if list should be expanded or callapsed by default.</li>
<li>Show number of posts: display how many post are published in the category.</li>
<li>Show empty categories: display categories with no posts.</li>
<li>Categories to include: categories to be included from the list.</li>
<li>Categories to exclude: categories to be excluded from the list.</li>
</ul>

JS Categories List Widget

Haven't seen any problems running this with WordPress 4.9.8, even though it's marked as untested for a long time.  It must have been well written.

Works well with 4.9.8

A simple Gutenberg block and JS widget (can be called from posts) for displaying categories in a list with some effects.

WP Wall vs JS Categories List Widget