It honestly makes me a bit pessimistic to see that it takes us years to build a factory like this. I would like to hope that we're capable of building the tenfold of this in months if shit hits the fan...

There's a huge difference between "let's build a factory to make as much profit as possible" and "let's build a factory to stop the invasion from killing us all". Most of NATO is currently on the former, not the latter.

Factories take time because the people them want them to be highly optimized and profitable. And they're competing with toothpaste factories, TV-frame factories and factories that make ringlights for influencers. Most of those problems and requirements disappear when you're actually at war.