The standout example of this from the Ukraine war is artillery shells.
We should maybe have a state owned corporation for making artillery shells in America, because there does not seem to be enough profit to incentivize private corporations.
I’m not following how that is a lesson from Ukraine. Their drones and missiles are made by private companies.
The true lesson i think is that in times of peace (or in times of wars of choice) procurement is dominated by excercises, lab tests, and design reviews. When you are doing that it is hard to tell apart the “good enough” from the “over engineered”. To every choice you can dream up a “counter”. Some real or imagined response or tactic by your enemy which would negate your system. And then your engineers have to design some counter-counter, or harden the system somehow. This leads to complexity which leads to high cost per individual weapon.
In contrast Ukraine is fighting for their existence. If they want to know if a new weapon is good enough, they send it to the front and try it. If it hurts the enemy more than it costs great. Order more. If it stops being effective, try something else. They are not picking the weapon system which will serve them for the next decade. They are picking what is available and effective today.
Different incentives, different opportunities which lead to different choices and different outcimes. But the difference is not if they are using private companies or not.