Using Kiosks to Emulate Chrome Sign Builder

Go to device settings, then click "apps and extensions page":

Image of the kiosk selection under Device Settings in the Google Admin console

Click "Add by URL":

Image of the add URL button under Kiosks in the Google Admin console

Insert the URL of your digital signage site/slide:

Image of the add by url menu and a pasted Google Slides URL

Read over to understand and agree:

Image of the agreement to add a web app

Set the signage URL as the auto-launch app, edit any desired settings at the right.

Image of the settings for a kiosk app in the google admin console

You may need to edit some other settings, like network, power saving, etc.