This is how you embed a Jira dashboard!
The Atlassian Marketplace app Dashboard Hub for Jira - Custom Charts & Share Reports allows external and secure dashboard sharing with public links.
How to add a Jira dashboard in Google Sites
How to add a Jira dashboard in Google Sites
Step 1: Create an awesome dashboard in Dashboard Hub and copy your Public Link.
Step 2: Insert the URL in your Google Site by using the Instert action in the panel.