middlewayapproach

You can use the block inside the Gutenberg editor as you would use a any other block. You can find it in the common section.
Icon made by <a href="https://www.flaticon.com/de/autoren/freepik" rel="nofollow ugc">freepik</a> from www.flaticon.com

Particle Animation Block

Nice plugin

A Gutenberg block to render a particle effect.

Ryan Novotny

Add the particles.js JavaScript library to add cool particle effects to any WordPress page ( demo: <a href="https://particlebackground.com/" rel="nofollow ugc">https://particlebackground.com/</a> ).
Uses shortcode or easy options for adding to the front page or blog page of WordPress.
Fully customize the particles using your own JSON or the built in color & density settings
Leave a comment in the support forum for any suggestions or bugs.
<h4>Features</h4>
Add particle background to home or blog pages with one click 
Add particle background to any page using shortcodes 
Customize the background color and dot color 
Add any HTML just like a WordPress post to display on top of the particle background (optional)

Particle Background WP


not real background, didn't work with css like written , and not work with gutenberg block 






Décue

Particle Backgrounds WP lets you easily add cool particle-style backgrounds to any page.

Particle Animation Block vs Particle Background WP