It depends on the version of atmos.
Full fat cinema atmos can scale to (iirc) 512 channels. (Things may have changed since I last was involved!)
In that case, it’s a 7.1 bed, and all the other channels are effectively coordinates in the room, and the processor steers objects between them in real time, rather than having defined tracks.
I’m not sure if there is a way to quickly find this. The best bet is probably trying the bigger instances, and seeing if it’s accessible through them.
You’ve made me think now: it might be a nice project for a some instance admins to flag when an instance they had received posts from goes offline. (I should probably check what I have from feddit.de!)