Embed content as a full page in Google Sites
Google Sites lets you add content as a full page. You can add custom code, another website, and Google apps like Google Maps, YouTube as fully functioning full pages. Rather than showing the content within a page, this allows you to display the entire piece as a page. With this update, editors have more freedom to organize and display embedded content.
Site editors can add content from multiple sources including custom code, other websites, and Google apps, such as Maps and Docs. To do so, go to 'Pages' and click the plus circle (+) on the lower right corner to add any content as a full page. Click 'Full page embed' <>
Notice 'Add embed', 'Add form Drive' and Google Apps under Insert menu options
An example of embedding google maps as a full page
Yes! You can embed another entire website as a full page within your Google Site
Name the page and add a url, embed code, 'Add from Drive' or embed content from another google apps such as Youtube, Calendar, Map, Docs, Slides, Sheets, Forms or Charts as well as Google Drive by clicking apps under the 'Insert' pane.