I don't see why Sound Wave would have any advantage, even efficiency, over a similar Zen 5/6 design. Microsoft must really want ARM if they're having this chip made.
It could just be a play to make sure there's a second source to qualcomm
The core count is relatively low though. 2P + 4E, whereas Snapdragon-X are 8 or 10 performance cores, indicating that this could be for a low-end tablet ... or game console?