Modern Google Sites no longer support the custom code needed to build effective proxies, and most third-party unblockers are either scams or security threats.
<iframe src="https://www.blocked-website.com" width="100%" height="600px"></iframe> google sites unblocker
A classic "low-tech" unblocker. Paste the URL of the blocked Google Site into Google Translate Modern Google Sites no longer support the custom
In schools and public libraries, streaming media is a network killer. If a Google Site embeds a heavy YouTube video or an interactive widget, firewalls may block the source to conserve bandwidth. google sites unblocker
