Uyshi

DxOMark normalises images to about 8 MP before calculating their “print SNR” (as opposed to what they call “screen SNR”, which is at native resolution), to account for different sensor resolutions, and notably the fact that while higher-density sensors would have worse per-pixel SNR, this doesn’t translate into noisier images. Indeed, as the article by Richard Butler you reference (don’t miss part 2) points out:

Note that the full frame sensor performs better than the APS-C sensor, even though its pixels are not bigger.

[…]

Having looked at what happens with cameras and crops made from the same sized pixels, what happens if we have differently sized pixels? Aren’t small pixels worse because they’re receiving less light? The answer is: yes, when considered at the level of individual pixels.

But, when you think about the effect on the whole image, not by as much as you’d think (if at all).

(See also: https://www.photonstophotos.net/Emil%20Martinec/noise-p3.html#pixelsize)

Do you do anything similar? My impression, looking at your measurements for the EOS R8 and the α7 IV, is that you don’t.