There is no lag with iTunes, thus why I did not mention iTunes. Most other video sources, lag.
iOS already supports stereo HomePod for audio from any app (music, youtube, websites, etc.) without any problems. The reason why we don't have proper stereo HomePod support in macOS is simply because of Apple's neglect, not because of any technical reason.Also, the lag time when playing video, youtube, or FInal Cut makes the Homepod useless currently for Mac video playback, whether 1 or 2 Homepods.
Get an Apple TV.