Leica is using Sony sensors, so them as a selection is mostly for the name and aesthetic. The UI is more limited and shooting RAW negates anything to do with “color science” selections for the default in-camera JPG encoders.
Fujifilm, Nikon, and Panasonic are using Sony sensors, however.
And, to a lesser extent now that mirrorless cameras are a thing - their unobtrusiveness.
Do you have a source for that? As far as I remember they have been very secretive about their sensor supply chain.