Lebensraum/autarky was simply .otivated by the desire to disconnect from international finance which is able to undermine the sovereignty of nations. The goal is being self sufficient.
Germany had plenty of iron and silver and tin. It lacked oil and agriculture. Easiest solution: take Ukraine.
Sure..Ukrainians forced to leave their homes might be sad. But this is what realpolitik is all about. It was just the German version of manifest destiny. We cannot pretend to be ethically superior.