AMD does market segmentation and limits consumer chips to dual-channel. You need to cough up the dough and get Threadripper for quad-channel. Or even more for Threadripper Pro to get octa-channel.

Afaik steam deck is quad channel, despite it being a pretty low end chip (with a decent GPU though)

As I mentioned above AMD's Strix Halo has quad channel memory and is consumer level. But yes, other than that everything is segmented away.