This site uses the Slides & Presentations Plugin, by Ella van Durpe, which allows you to create presentations with the block editor. The plugin implements the “present from the web” (open source HTML presentation) framework known as Reveal.js. A commercial version of Reveal.js with more features is available at slides.com.
The advantage of using WordPress and the Slides plugin is that you can aggregate all of your presentations in one place – for free.
At this point in time the plugin is in its early days, but the author hopes to add more features in the near future.
If you would like a fantastically detailed introduction on how these slide decks are created, please read How to Create a Slide Deck in Gutenberg on WordPress by Taylor Elizabeth Rose.
This plugin was featured in Matt Mullenweg’s State of the Word 2019 conference keynote held in St. Louis, MO. The relevant point in the YouTube video (at 39.53) shows the “reveal” (no pun intended) of how WordPress was used for the editing and presentation of Matt’s slides.