Fascists very much hearken to the idea of an eternal conflict and a single national leader, while authoritarian leftists, in theory, are seeking an actual end goal of a stable society without a strongman.

The idea of “class struggle” (being an eternal conflict) and proletarian dictatorship (afaik always with a single national leader) sounds pretty fascist based on this definition. Of course intentions matter, but I’d say end results matter a bit more.