Torch of the Protectorate actually has Hitler as a possible leader for Austria, so that mod might interest you.I have been brainstorming an ATL which I think would work great in HOI4, unfortunately I have no modding capability.
It would be what if Hitler led Austria and not Germany. The in-lore reason would be that when he was signing up for the German Army they discovered he was Austrian, which would disqualify him. He then joins the Austro-Hungarian Army, specifically the German Landwehr, and fights on the Eastern Front. After the war he joins a far-right win olitical coalition, but they kicked him out due to his radical policies but he creates his own party, the Austrian Social Nationalist People's Party (Österreichische Sozialnationalistische Volkspartei, OSNVP or Sozinat for short). They come to power in a coalition government with Dollfuss' Fatherland Front in 1934, but Hitler quickly has Dollfuss killed by a deranged Communist, and assumes total control by early 1935. So by the time HOI4 starts Hitler has been the Staatführer. Their symbol is a red cross potent (a Kruckenkreuz) in a white circle upon a black field.
The National State of Austria begins to grow, annexing Bavaria in 1937 (Bavaria broke away from Germany in this timeline due to a German Civil War in 1936), the Sudetenland, in 1937, while bringing Czechia in as a Protectorate, and Hungary in 1939. The annexation of Bavaria was more of a union, with Bavaria joining Austria to prevent being taken over by the Hohenzollern Protestant Germany.
Germany restores the Hohenzollerns to the throne in 1936, due to a coalition between the center-left and center-right, spearheaded by the SDP and DNVP.
The German Civil War is fought between the SPD/DNVP vs KPD vs various fascist movements, fought between 1936-1938. Germany later joins the Entente to fight Austria.
WW2 lasts from 1941-1945, the Axis Powers big three are Italy, Poland and Austria.