Realistically, for the first 3-4 turns it just means that SeaLion should be off the table and Italy won’t get very far, with the usual caveat that if UK screws up its UK1 buy, its still a valid choice (and if the U.S. doesn’t buy ships for Atlantic on US1, it might be a very good choice)
A concentrated attack shouldn’t be coming until, what, US4 (if you’re completely empty on the Atlantic side of Germany) but US5 or 6 more likely, right? So by then, hopefully, Germany has Russia stacked in Bryansk, you’ve taken Novgorod (or Ukraine if his stack isn’t a threat to yours) and are bombing Russia, and have about 7ipcs of theirs, so if the US/UK make a move towards Europe, Germany can dump a whole lot of inf/art all over France and W.Germany on the turn after he moves to Gibraltor. Just always keep a destroyer handy as a blocker to keep him out of Denmark/Norway for an extra turn, if you have to and make sure Russia can’t destroy your Germany stack.
So when the US/UK go to Gibraltar, Italy will need to buy infantry to make sure they’re not too vulnerable.
If the US ground troops/UK fighters are lower in numbers, you can keep a couple of transports sitting in sz114 and a few planes in W. Germany so you can retake Norway.
If their attack ships are weaker, you can stack sz 112 to prevent landings up north (especially if your battleship and cruiser have survived. With 3 scrambling fighters and maybe even a carrier with 2 more fighters is pretty tough, but especially if you dump 5-10 subs there as casualty soaks in a desperate attempt to stop an invasion, but also useful to turn around and sink his fleet)
An aggressive J1 means that if the U.S. is sending assets to Europe, you should be able to win on the Pacific side. India around J6 or J7, then ANZAC pretty easily, if they don’t have strong U.S. help.
/I’m a STRONG advocate for J1. If you don’t, any money the U.S. doesn’t get just ends up with UKPac and ANZAC and Japan can handle anything except 100% U.S. pressure without giving up anything on the mainland because you can keep buying carriers and using fighters you already own to maintain SZ6 as a fortress.