When I was buying HomePod Mini at the Apple Store, several staff at different stores gave me wrong answer - or couldn't answer the questions I had:
1 - Can I control the HomePod Mini with my Apple TV4k1?
2 - Can I have my Apple TV send music to my stereo*, AND to the Home Pod Mini at the same time.
(* My apple TV is daiy chained ATV4k > Stereo > TV (all three have AirPlay2))
I was told I couldn't, but had a weird gut feeling I had to try, and glad I did because it turns out that I can - and the UI (which is from the subside menu where you pick use profiles) is really handy and easy to use. Does easy grouping, and individual volume changing with ATV just like the Phone iOS.
To be fair, they're probably thinking of the Home Theatre Audio feature and the ability to use the HomePod as a Default Audio Output. This is significantly better than just using one or two HomePod minis... both in terms of the overall audio quality (you get Dolby Atmos) and the fact that they effectively replace the internal speaker channel entirely. They're effectively always connected so you don't have to switch back to them each time you turn your Apple TV on.
The HomePod mini, on the other hand, is really just an AirPlay 2 device as far as the Apple TV is concerned, so you can stream to it just like you can any other AirPlay 2 speaker or receiver.
Still, Apple really does need to educate their staff better on how this all works. Since every recent support document on the new Apple TV 4K and tvOS 14 audio features explicitly says "HomePod mini not supported," I can understand their confusion, but there's still no excuse for somebody who works at an Apple Store not to be better informed.
This is one aspect I don't think that gets sold enough, especially for smart home advocates. For people that have Apple Music, and a good stereo - they can also get home PodMini and pick and choose where music is in the house at a very good price. Comparably, the Yamaha MusiCast speakers are much more expensive - work only with the stereo... and I don't think have Thread). the TVos also works to control different casts if that is going on.
Yup, and that's been a great feature for the Apple TV ever since AirPlay 2 made its debut in 2017. I've been using it with my Apple TV HD for a while — in both directions.
Mind you, it's also arguably just as easy to play music on the HomePod mini from the Music app on your iPhone, iPad, Mac, or even just by calling it up with Siri. It's about the same no matter what the source device is — except of course you can also play direct audio from the Apple TV to your AV receiver.
Further, you can also simply AirPlay TO the Apple TV as if it's a receiver on your own. This is what I did far more often. In other words, start playing something on my iPhone and then AirPlay it to the HomePod in the dining room, the HomePod mini in the kitchen, and the Apple TV in the living room (where it played through the connected speakers on my AV receiver).
This is huge, cus if it's not just music everywhere but also a sports game on the ATV4k, I can have that in the kitchen and other rooms too so I don't miss a minute. Some apps work - some apps don't - but that comes down to the developer. I've noticed anything dev by Bell Media (I'm in Canada) doesn't work for these functions OR PIP, but most apps do. Bell Media even recently rehauled the TSN app and it still doesn't have these features.
Yeah, I'm in Canada too and I've been down the same road. Bell Media rolls their own media players as they're more paranoid about copy protection.
Apps that use the built-in tvOS media playback frameworks will all work fine, while others like Plex and YouTube are at least using the right playback APIs so that audio gets routed properly. Bell and Rogers are just weird this way.
You still can't cast to AirPod Pro + a HomePod mini, it's like it's either or there...
Yup, same with AirPods Max. That's actually a Bluetooth thing — you can't use both Bluetooth and AirPlay 2 at the same time. I suspect Apple just can't be bothered dealing with the sync/latency issues to make that work properly.
When I airplay2 to from my iPhone (Xr) to my Stereo, Kitchen HomePod Mini, and be the Bedroom HPMini, its syncs perfect - but if I have the apple TV to stereo, (or phone to Apple TV (which is daisy'd to stereo)); there is a slight offset from the main stereo sound and the two HPMini.
That's interesting, as I've never had that problem on my Apple TV HD connected to my Denon receiver (an AVR-X2000), and it's something I've used on an almost daily basis over the past three years. You might have success with tweaking some of the Apple TV audio output settings to make sure it's sending the best quality audio stream out over HDMI.