Exactly.
Near all the machinery had to be imported. Only grain was available to be sold for the cash necessary. That leaded to grain requisitions and, finally, to starvation. The starving population was allowed (not always) to move to cities seeking for industry jobs what constituted cheap labour force.
Ukraine
as well as other places: Southern Russia and Kazakhstan which were top producers of grain together with the Ukraine.
and killing millions more in gulags somehow industrialized the USSR?
Gulags were founded to do a job: build a canal, a factory or even to design a new fighter planes. (In the last case engineers were convicted and put to work).
If what you say is true, how is it possible that other countries managed to industrialize without killing millions of people?
Because none of them managed to complete it within 20 years.
“Because none of them managed to complete it within 20 years.”
...and because no one but Russians would find the death of millions worth the price of industrializing within 20 years. Apparently Russians don’t value life if your argument is that this sacrifice was worth it or in any way noble. It is a national disgrace, yet you seem proud of this obscene holocaust. So strange, so sad.