People put too much stock in the Atmos name. All its is is object based tracking, but if you don’t have a 5.2.2, 7.4.2, 9.4.2 system in your home it doesn’t really matter. The majority of people I see worrying about Atmos have a soundbar which isn’t going to give you full atmos. There are very few people in the world who could sit in a room as tell you the difference between DTS-MA, True-HD and DD Atmos.
Do you have a full atmos surround sound system in your home that is calibrated to take advantage of object based tracking?
If you’re using a receiver (amp) then your ATV should be connected to your receiver directly via hdmi and then from your receiver to your tv via hdmi. Everything will then communicate via CEC over hdmi. The ATV will receive its signal via Bluetooth and transmit it to the proper device. This is assuming you have a receiver with hdmi switching.