Yep, but the AppleTV already acts as a "Home IoT server" alongside the HomePod. (and an iPad can it too.)
HomeKit uses one of those 3 devices to allow external access to your local sensors. For instance, I get notifications when the front door is opened and closed. I can unlock it remotely too. Am slowly adding extra sensors.
From the cousin comment:
> security video peripherals
See HomeCam https://homecam.app
Unfortunately you can't run any old app in the background on any of these closed devices. I have a quad-core Mini that does duty as media library, software update caching, video encoding and photo export... if I could do those on an ATV it would be great.
It seems like for the homecam.app there's no storage of the video stream, or one would need to add another box/device for that?
I haven't bought into any home automation hubs yet, it just doesn't seem quite there in terms of being worth it from any of the vendors, and I think if it were, I'd just run a full up server for a central hub.