Awesome Table Slideshow
You can now build slideshows with Awesome Table. And they even work in the new version of Google Sites! And they are fully responsive!
The slideshow can be placed in the header. Just drag it there from the page area. See it here
Instructions for embedding in a NEW Site:
You can start by signing in here with your Google account and selecting the Slideshow template.
COST: Customer can use the Service without fees for a limit of 1000 Pageviews per month on a single G Suite domain, a Pageview being an instance of the Service loaded (or reloaded) in a web browser.