I think you have it wrong: there's nothing in spatial audio on AirPods that requires processing at the source, other than for the source to provide its relative position in local space/coordinates. no signal processing going on at all. Spatial audio works, as specified by Apple, on Dolby 5.1, 7.1 and ATMOS..and perhaps other multi-channel sources.
Processing to make the listener believe that two drivers sound like 6, 7 or more, and perhaps more importantly, to make it sound as if no matter how you turn your head, or move your iPad, iPhone, etc, that the audio still feels like it's coming directly from the device instead of staying constant relative to your own face's front-and-center is done using both psycho-acoustics and more straightforward inverse gyro compensation in the signal as a whole.
I've heard form others that it does in fact work on tvOS beta -- it's likely that the iOS 14 beta hosts the firmware update for the AirPods Pro -- though I don't know how the original position of the tv screen is established relative to the listener: the Apple TV box isn't guaranteed to be nearby enough to center-screen on the TV, and simple Bluetooth positioning isn't enough anyway.
I tried this for the first time over Christmas using AirPods Pro and for me it’s a bit mixed but I think it is more a limitation of the AirPods Pro than Spatial Audio per se.
The tracking is clever, although less pronounced and “surroundy (tm.)” than I was expecting. However the AirPods Pro have a bit of a boom tizz balance and when spacial audio is activated, that boom tizz is exaggerated further resulting n a very thin midrange. Watching Last Jedi some of the action scenes were positively uncomfortable to listen to. If I turn spatial audio off the same scene becomes a little more listenable but still not great. Plugging in my beloved Shure SE425’s and the same scene is very natural and enjoyable. This makes me feel this is more a limitation of the Pro buds rather than the spatial audio tech and maybe it works much better on the AirPods Max headphones.
It’d be interesting to hear if anyone else has the same experience of it and if they find the experience via the Max is better balanced than the Pro’s.
In either case, I have a set of Max headphones on order (due in about a million years due to the waiting list), so I will post up what I find once they arrive.