For those wondering about the math: a SODIMM channel (e.g. DDR5) is 64 bits. An LPDDR channel is 16 bits. M1 has
8 of those (128 bits), M1 Pro has
16 (256 bits), and M1 Max has
32 (512 bits). That means the M1 is equivalent to dual channel RAM, the Pro to quad channel RAM, and the Max to octa channel RAM, in typical desktop/laptop RAM terms.
Modern embedded SoC integration is insane. Yes, the "two" memory chips you see on the M1 are really 8 discrete dies/chips (4 stacked together inside each of the two packages), and the "two" big fat things around the Pro are actually 2x8; double them up for the Max and that's how you get to 32 channels. Good luck putting that through a connector...