How to integrate an Azure Devops Calendar into Outlook

The Azure DevOps calendar is a extension: Team Calendar, and the source code is in github: https://github.com/microsoft/vsts-team-calendar

For this extension, it stores data in Data storage and you can add/get/update it through REST API.

(You can check requests through Developer tool: Press F12 to open Developer tool > Network > add/update event >Check requests)

For example:

https://extmgmt.dev.azure.com/{org}/_apis/ExtensionManagement/InstalledExtensions/ms-devlabs/team-calendar/Data/Scopes/User/Me/Collections/%24settings/Documents

https://extmgmt.dev.azure.com/{org}/_apis/ExtensionManagement/InstalledExtensions/ms-devlabs/team-calendar/Data/Scopes/Default/Current/Collections/{team id}.{month}.{year}/Documents

So, you could build a outlook add-in to call these data storage REST APIs to integrate them.

For this issue, if you mean the calendar in the Boards, I am afraid currently there is no out-of-box feature to achieve this.

You can integrate Azure DevOps and outlook through Microsoft Flow, but there is currently no such flow about calendar.

In addition, in our official feature suggestion for Azure Devops forum, there is this existing suggestion: Import Outlook Calendar Events Into Azure Calendar. You could vote that suggestion ticket and share your comment there. The product team would provide the updates if they view it.