My two cents says - if Germany attacks G1, then builds armor repeatedly, they’ll see a shortage of infantry soon enough. Their entire western flank, as said by others, will be eroded quickly. Killing tanks with infantry/artillery and a couple planes will be a nice laugh.
Don’t forget the power of the strafe to whittle down your opponent’s fodder, then fall back into reinforced positions.
As far as infantry vs. aircraft, oh yes. Most of my early games saw me buy an aircraft for the first three rounds - I like 4 fighters/2 tacs with Russia - but I’ve abandoned that over my past 3-4 games in favor of the all meat and potatoes purchase… land units only. After all, this isn’t a trade war we’re interested in, but a game of taking and holding key positions. The days of trade wars are over, imo. They were left behind in Anniversary. Aircraft can’t take a piece of land… all it can do is kill and retreat. I now prefer to set up overlapping defensive structures with a slowly growing mobile reserve, to be able to threaten multiple places.
Russia has to learn that they don’t have to fight for every IPC. Some are ok to let go. A trade war will result in a gradual erosion of Russian land units, and death.