Hello, Am I dreaming? Since updating my AppleTV and HomePod Mini OS to the latest 15.1, I need go through the Settings/Audio Output in my AppleTV to connect the HomePod Mini. Before, while watching my movies, I could choose/select in the same menu as Languages, and Subtitles. What happen!
Not sure what is happening with your system (my system with original HomePods has not changed with 15.1) but you can press and hold the Home button on the remote to bring up the Control Center, where you can select audio output without going to Settings. I think the Control Center function replaced selecting audio output via the swipe down menu (subtitles etc) some time ago.
Note also that two HomePod minis can now be set up as default stereo output for the Apple TV. Previously only the original HomePods could do this:
Bingo! I can use Control Center. Thanks a million.
This was a great tip. I never knew that.