Open your Google Slides presentation.

Click on "File" in the top menu and select "Publish to the web".

In the pop-up window, go to the "Link" tab.

Check the box for "Start slideshow as soon as the player loads" and "Restart the slideshow after the last slide".

Set the slide transition timing from the dropdown menu.

Click "Publish", then copy the generated link.

Open the link in a browser, and your slideshow will loop continuously.