I think Wolfenstein is well beyond a wank. Nazi Germany somehow winning the War in otl and not immediately imploding from some sort of civil war or power-struggle is already borderline asb. The Nazis in the game by the 1960's have already achieved world domination and have begun colonization of the solar system with things such as military bases on the moon.
I actually think the trope of the full-blown Nazi civil war is a little overdone now. I suppose it's a nice antidote to Nazi-booism - but I think the main problem is that there are lots of violent political struggles that fall short of a full-blown civil war. Most violent political struggles. Heck, we can look at ACTUAL Nazi Germany for an example of this (the Night of Long Knives).
Nazi Germany will very easily have something like the Night of Long Knives on crack - but I think a full-blown civil war is a stretch.
I think the same logic also applies to the Soviet Union. I'm of the opinion that a Nazi victory would both moderate the Soviet Union by uniting basically everyone imaginable against the Nazis - so I'd actually envision a very popular and united Soviet state (supported by the Western Allies) because honestly any political disagreement can wait until the Nazis are expelled. Could honestly be one of the easiest ways in a TL to get democratic monarcho-communism lol.