As the owner of a couple of HomePods since release and multiple Apple TVs....
If you're planning to use HomePod(s) instead of a proper sound bar for your TV...
Don't. It's a total pain in the ass. Every time you play something to the HomePod (e.g., from your laptop/iPhone/iPad/etc. or by asking siri to play) or the ATV restarts or whatever you need to duck into settings to re-set the output to the HomePod.
Spend the money on a sound bar instead. As a bonus, you'll get the ability to stream audio to said sound bar via the appleTV anyway. And the sound quality will be better/louder than a HomePod if you get an equivalently priced sound bar setup.
By all means get multiple HomePods for the house if you want sound in multiple rooms, or stereo or whatever; just don't go expecting the appleTV -> HomePod experience to be good, because it totally sucks imho.