Condless

WooCommerce plugin that sets default attribute for variable products automatically if only 1 option is in-stock.
<a href="https://en.condless.com/default-attributes-for-woocommerce/" rel="nofollow ugc">Documentation</a> | <a href="https://en.condless.com/contact/" rel="nofollow ugc">Contact</a>
Variable product of T-shirt with color attribute (White/Blue/Black) and size attribute (S/M/XL): 
If only Black T-shirts are in-stock: default color (Black), default size (none). 
If only Small T-shirts are in-stock: default color (none), default size (Small). 
If only White and XL T-shirts are in-stock: default color (White), default size (XL).
<h4>How It Works</h4>
<ol>
<li>Before product variations is displayed to the customer, the plugin will check each attribute, and if there is only 1 in-stock option it will be set as the default.</li>
</ol>
<h4>Features</h4>
<ul>
<li>Stock: Set option as default when it’s the only 1 in-stock.</li>
<li>Per Attribute: Set specific option as default in all products with that attribute (from the Edit Attribute screen)</li>
<li>Top: Set as default the first option of each attribute.</li>
<li>Out of stock: Disable out of stock variations.</li>
<li>Add to Cart button: In archive pages display for variable products the attribute name instead of: “Select options”.</li>
<li>Select options: In single product pages remove the select options text if default attribute is set.</li>
</ul>

Default Attributes for WooCommerce

WooCommerce plugin that sets default attribute for variable products automatically if only 1 option is in-stock.

ska-dev

websevendev

jimedwards

This plugin adds additional advanced inspector controls to Gutenberg blocks that allow to add any custom HTML attributes to the block’s front-end output. This allows you to add inline styles to fine-tune the block’s appearance, set aria attributes to improve your site’s accessibility, add data attributes to integrate with any JavaScript modules or even JavaScript DOM event attributes such as <code>onclick</code>, <code>onchange</code> or <code>onload</code>.
<a href="https://playground.wordpress.net/?plugin=attributes-for-blocks&url=%2Fwp-admin%2Fpost.php%3Fpost%3D2%26action%3Dedit" rel="nofollow ugc">Demo</a>

Attributes for Blocks

It's perfect for what I need! I hope you'll keep it updated as this behaviour should really be native in WordPress!

This should be native!

This is just Gold

Allows to add HTML attributes to Gutenberg blocks.

Default Attributes for WooCommerce vs Attributes for Blocks