Here's test made by Polish camera and lens review site Optyczne.pl (also known as Lenstip)
Test Pentax K-1 II - Wst
K-1 II has been tested with DFA 24-70 and Sigma A 35mm lenses.
As points of reference, Lenstip chose Nikon D850, Sony A7R III and K-1.
Denoising of RAWs at ISO settings bigger than 400 confirmed. The loss of detail induced by denoising, measured as difference in resolution for ISO 800 compared to 400 (where no denoising happens) is at maximum 1.1 lpmm.
K-1 II static AF seems to work better in tungsten light than other cameras. In daylight results are not impressive in comparison, and a few totally missed shots happened (with DFA 24-70). In general, AF performance (including AF-C) was given 'average' rating.
Standard Pixel Shift mode gives around 5 lpmm gain in resolution. MTF analysis does not indicate sharpening. Dynamic Pixel Shift results resolution-wise are not much better than standard shots. Motion correction works okay.
K-1 II noise at three lowest ISO settings is lower than D850, A7RIII and K-1. Charts indicate it is true also for higher ISOs, but Lenstip said that due to forced denoising it is hard to come up with objective comparison.
Lenstip does not see K-1 II as an upgrade worth the money, and advises to stick to its cheaper predecessor.
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Another labtest of K-1 II: Pentax SLR Talk Forum: Digital Photography Review
One question - why do they think that it's NR in RAW from ISO400?
Noise is there, it's not noiseless photos. Just the cleaner shadows and tiny less details. It could be another hardware+software work of K-1II. Can we name it NR in RAW or not?