OK done comparatives at ISO100, 400, 1600 and the visual result is startling - only ‘native’ 100, maybe 200 will do, affects apparent sharpness as well as noise.
That means condemned to tripod and remote/tethered camera control, with many shots above 1 sec, for domestic interiors - either that or handheld with a strong diffused flash rig.
Any recommendations on the latter? On the camera, or on a stand(s)?