So where are all the Republicans in the public sphere standing up for moderation?

You know even from liberal media that there is a moderate republican faction, and they are indeed getting hammered exactly by people just like you but from the right.

See, now, the 1920s and 1930s taught us that reasonable debate with fascists is impossible.

Where did you learn that? A reasonable debate with any extremism is impossible, it isn't just fascism. Point is you can't let an ideology slip into extremism to begin with. If you refuse to debate your position, that's already a sign of extremism, and calling your counterpart fascist doesn't really make yourself better.