Polish-dominated Russia?

How much of Russia could the Polish-Lithuanian Commonwealth have realistically gained control over? And what might a PLC-ruled Russia have looked like? Could it have become as Polonized as western Ukraine was IOTL, with the nobility speaking Polish and most of the population being Uniate?
 
How much of Russia could the Polish-Lithuanian Commonwealth have realistically gained control over? And what might a PLC-ruled Russia have looked like? Could it have become as Polonized as western Ukraine was IOTL, with the nobility speaking Polish and most of the population being Uniate?
The maximum realistic extent, as in “territory which the PLC could hold for a considerable period of time”, was reached after the Smolensk War. The territory was polonized but within a few decades it was reconquered by Moscow. However, a considerable percentage of the local nobility remained Polish/Polonized to a degree that was visible at least till the early XVIII.

How the territory looked like? The same mess as the rest of the PLC.
 
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