Dpreview have done some tests and I’ve found some artefacts suggesting that dynamic pixelshift might indeed be using non-debayered data. At least that’s my conclusion after seing these familiar pixel level artefacts.
Perhaps they aren’t a result of raw pixel merging but they look like it to me. Note the review claims it’s debayered but they don’t reference any source.
edit: a better link is the following https://www.dpreview.com/articles/7242776989/pentax-k-1-mark-ii-dynamic-pixel-shift-mode