Have you looked into DValdron's
Axis of Andes? Brazil still isn't committed there yet, but it could plausibly wind up on the Allied side. (I happen to know some spoilerish inside stuff about what will happen there, though not about Brazil directly, though it would affect the nature of the anti-"Axis" side Brazil could join).
Now in that timeline, Brazil is not more developed or prepared to make a substantial military commitment to Europe than OTL and as the South American war apparently drags on right into the mid-40s I guess there they'd be too bogged down in the war against Chile and Ecuador to divert anything northward anyway. But the depth of research DValdron did on the western nations of South America is an example of how to come up with plausible diversions there in general.
I'm afraid I don't see Brazil going actually Communist, but a strongly leftist coalition government there might be a help.
It would probably butterfly away the German Zeppelin services there.
