Isn’t atmos not specifically multi channel as in traditional 5.1/ 7.1, but Atmos is positional sound that then generates the correct speaker positioning on the amplifier? For instance my home setup has support for 5.2.4 channels, two bass and 4 risen speakers. Additionally you can adapt the positioning of the rear speakers and the amp will adjust the audio to compensate.

So you could just export atmos to a 5.1 mix, but that is not a copy of atmos tracks.