This article explains how to connect an Apple HomePod to an Apple TV using two methods, each requiring an Apple TV 4 or later. It includes a few caveats to the process and a list of requirements.
How to Set Up HomePods as TV Speakers (HDMI ARC and eARC)
The Apple HomePod is a voice-controlled smart speaker designed to easily deliver clear, room-filling sound, much like its competitors the Google Home and Amazon Echo. As a standalone speaker, the HomePod can be the audio output for a digital television.
However, the HomePod can't connect directly to a TV. As a wireless Bluetooth device, the HomePod must connect to an Apple TV device via AirPlay to play audio from a television.
Once you've set up your HomePod, you can make it the audio output source for Apple TV in a couple of ways. This lets you play audio from Apple TV content on your HomePod instead of your TV. The first method involves using the Apple TV settings.
