That's unlikely to be what was meant. It's probably m.2 2242, a shortish but "normal" drive size in the embedded space.
As others have said, it was probably supposed to read "m.2 2242" which is physically in-between the size of the 2230 drives that the Steam Deck uses and the 2280 ones that most modern desktops and laptops use.
Notice no 20 mm width is allowed as part of the M.2 standard. The device specs are likely a typo.
That's unlikely to be what was meant. It's probably m.2 2242, a shortish but "normal" drive size in the embedded space.