We do not have a direct integration with Hangouts.
We do have the webhook notification channel; (link here for more info), the webhook is simply a HTTP Post with a JSON document with information on your alerts.
From my searching on Google Hangouts integrations, they can not accept incoming webhooks. However, it may be possible for you to send the webhook to a 3rd party which parses the data and send the alerts onwards using the Google Hangouts API.
I’m going to get a feature request started for you on this, and I’ll add a poll to this post for others to share their interest. Let me know if there is any more I can do to help.