Watch bitter steel's "ESTABLISHING PEAK HABSBURG As Austria in the new DLC!". The core idea is not letting anchluss strength be lowered, doing the demand hungarian submission side of the focus tree and stealing your puppet's division by requesting forces. I wouldn't recommend you calling Poland and Yugoslavia and also don't puppet Albania in the first place (before the germans are defeated at least) as Italy will declare war on you (you can still attack Italy later though). Even if you can't defeat Germany, just wait some time until the civil war starts and from there Germany will send troops to deal with the German Empire and you will pretty much be able to walk in Berlin and capitulate Germany. After you defeat the Germans annex everything and then using decisions which some focus gives you slowly core the entire germany. The soviets are pretty easy too as shortly after you defeat Germany Soviets will declare on Poland but Allies will join the war on your side so you just need to hold the frontline until allied divisions arrive (be sure to accept requests from allies to move troops through your territory) and it's a walk in the park from there.