DevMoaz

<p><strong>Collapsi for the Block Editor</strong> adds an editor-only chevron toggle to every Gutenberg block. Hover any top-level block, click the chevron, and the block tucks away into a compact bar showing the block’s icon, title, and a short content preview (paragraph text, image alt, “5 blocks”, and so on). Toggle it back open with the same chevron.</p>
<p>Built for the long pages and Site Editor templates where scrolling past 50 blocks to find the one you want is the daily annoyance. Collapsi is <strong>strictly editor-only</strong> — your published site is untouched, no extra CSS or JS ships to the frontend.</p>
<h4>Why this plugin</h4>
<ul>
<li><strong>Stop scrolling endlessly.</strong> Collapse the sections you’re not working on. Find the one you are in seconds.</li>
<li><strong>Works on every block.</strong> Core, third-party, custom, ACF — anything Gutenberg renders, Collapsi can collapse.</li>
<li><strong>Survives reloads.</strong> Collapse state is saved per post, per template, per browser. Come back tomorrow, your layout is where you left it.</li>
<li><strong>Per-instance opt-out.</strong> Set “Never collapse this block” on a hero or any pinned block from the block settings menu.</li>
<li><strong>Keyboard shortcut.</strong> <code>Alt+Shift+C</code> toggles all top-level blocks at once. Discoverable in WP’s shortcut help modal (<code>?</code>).</li>
<li><strong>No telemetry. No remote calls. No premium upsell.</strong> Free, GPL, forever.</li>
</ul>
<h4>How it works</h4>
<p>The plugin hooks <code>editor.BlockListBlock</code> with a higher-order component that wraps every top-level block. State lives in a <code>@wordpress/data</code> store and persists to <code>localStorage</code> keyed by either the block’s structural path (<code>"0.2.1"</code>) or its user-set name from Gutenberg’s rename feature. A <code>PluginSidebar</code> exposes Collapse All / Expand All / Focus Mode. Settings live at <code>Settings <span aria-hidden="true" class="wp-exclude-emoji">→</span> Collapsi</code> and persist via the REST API.</p>
<h4>Compatibility</h4>
<ul>
<li>WordPress 6.5+ (iframed editor)</li>
<li>PHP 7.4+</li>
<li>Post Editor and Site Editor</li>
<li>Browsers: Chrome 90+, Firefox 88+, Safari 14+, Edge 90+</li>
</ul>
<h4>Not in scope</h4>
<ul>
<li>No Classic Editor support — Gutenberg only</li>
<li>No frontend collapse (this is an editor productivity plugin, not a UX framework)</li>
<li>No premium tier</li>
</ul>
<h3>Development</h3>
<p>Source code, issue tracker, and build instructions live at https://github.com/devMoaz/collapsi-for-block-editor. The compiled assets in <code>build/</code> are produced by <code>@wordpress/scripts</code> (webpack) from the <code>src/</code> directory in the GitHub repository. Run <code>npm install && npm run build</code> to reproduce.</p>


Collapsi for the Block Editor

Editor-only collapse/expand toggle for every Gutenberg block. Tame long posts and templates without losing your place.

Miguel Useche

<p>This plugin provides a widget and a filter to display a collapsible list of categories in your sidebar or posts by using vanilla Javascript.</p>
<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  <em>[JsCategoriesList]</em></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>Open links in a new page: render category links with target=”_blank”.</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.

Collapsi for the Block Editor vs JS Categories List Widget