Yeah, Italy should be the first to be totally taken out, but you have to neutralize Japan first. You don’t have to actually take Japan out to make them no longer a threat. The US should build heavy in the Pacific for the first 2-3 rounds, mostly warships and air power, then start investing in troops to head over to Europe. A large US Naval presence in the Pacific should be able to over power the Japanese Navy as Japan will not be as able to replace losses as the US can. ANZAC can help by nibbling at the fringes of any Japanese Naval movements.
If the Allies can manage to hold on to just one of the DEI islands, that will ruin the Japanese NO. The Chinese and Brits from India can whittle away at the already small amount of Japanese land troops. Perhaps even Russia can help out in the north, unless you called all those infantry back to Moscow.
Also, the US should use lots of subs to do convoy damage. With Japan losing ground on the mainland, their navy either out of position or weakened too much and US with a large fleet in SZ 6, Japan will be making very little and not have the resources to become a real threat again. Even better is if US can take Iwo Jima or Korea, stage some bombers there and SBR the crap out of Japan’s IC, air and naval bases.
With Japan in check like this, USA can send large amounts of men and equipment to Europe. Land in Rome and use the Italian factories to move north to Germany. German defenses shouldn’t be too heavy as they will be focusing so much on trying to take Moscow. If they do divert substantial resources to holding off the Americans and Brits, that clears the way for a Soviet push away from Moscow and possibly toward German territory. Either way, Berlin is eventually screwed.