There is no widget needed. You can make the Google Slides document public, and then link to it. You can also use the HTML embed code provided by the document to embed the presentation onto a web page using the HTML Source widget.
The slide presentation needs to adhere to the same ADA standards as a static web page, so be sure to use the proper headings, and semantics for screen readers to easily navigate the document.
- HTML Source - Detailed description of the widget.
- Publish and embed Google Docs, Sheets, Slides & Forms
- How to use Google Slides