Indeed, it must be one of the compute units available on the newer Apple processors. My iPad Pro 2nd gen also doesn't support it. I really hoope that they upgrade the Apple TV to support spacial audio soon. It really is a nice feature. Also, Mac support would be great. The bigger the screen, the more likely you are watching movies on it.

While they are at it, Apple finally should properly support homepods on macOS. They still aren't shown as pairs - at least on Catalina.