By having a deterant? Not nuclear of course, but an "Ukrainian economic powerhouse" would eventually have the capability (after a transition period to decouple from Russian industries) to keep mass Producing IRBMs and even ICBMHow are you going to stop the Russian invasion without numbers?
There is no Russian invasion of Ukraine, no Donbas war if any troops crossing the border means The Kremlin is a crater within the next 30 minutes.
Conscription can be good or bad depending on how it’s done, plenty of very wealthy countries have conscription, but a wealthy country the size of Ukraine wouldn’t need conscription to make an effective deterrent.