Thank you for reaching out on the Microsoft Q&A forum.
Currently such functionality similar to Traffic manager is not available for Azure Front Door. As mentioned by you above the Origin Health Percentage metric will provide this information.
You can also take a look at Health Probe logs to get more information on origin failure.
It will be also helpful if you can create a feedback item for this request on the feedback portal.
Hope this helps! Please let me know if you have any additional questions. Thank you!
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