Tidal uses AC4-IMS which is a better codec, but this is a 2 channels format to mix binaural with stereo. Apple uses DD+JOC, which is a 16 channels atmos encoded as a native 5.1 with metadata to recompose the 16 channels (clusters of objects).
Spatial Audio is the Apple renderer of dolby atmos files. They don’t use the Dolby Atmos renderer because they added head tracking and other magic to be able to render the music on their laptop speakers, iPhone/iPad speakers (this is not really a Dolby format).
DD+JOC is the standard for consumer and it is lossy, because that’s 16 channels of 24bit/48kHz which can be as much as 15Mb/s. The audio bandwidth is as much as the video bandwidth and that‘s a lot for consumer equipment to handle.
There is a new Dolby standard based on AC4 instead of AC3 that DD+JOC uses, but I have not seen decoders having it.
AppleTV 4K, can handle Atmos, and send it to a receiver via HDMI
On a Mac, you need a audio interface with at least 10 outputs (for 5.1.4). I use a Focusrite 18i/18 with Yamaha hs7/5 powered speakers.
I have released a few tracks in Atmos.
Few people have the full setup to hear my music with a home theater, many just listen to it with airpods.
Binaural rending is constantly improving. Apple just added HRTF like customization, which improved a lot my listening experience on airPods.
Many people in this thread have pointed the same, but I though I would share my own experience.