World War II was won because of US and (less advertised) Soviet manufacturing capacity.

Ukraine is more constrained by weapon supplies, especially drones and artillery, than by manpower.

I'm not sure both sides are playing the same game. In the game I think might be afoot, if your economy is management consultants, therapists, and hair stylists, that's "bad" GDP. Resources and manufacturing are "good" GDP. Resources are complex in that stone are renewable, and some go away when you export them.

I'm not even going to talk about education or, related, R&D capacity.