Hi just a minor nitpick/ramble from someone whose IRL job means I know a bit about the industry. The issue with collecting minerals is actually refinement; things like cobalt are relatively rare on earth, but lots of places have some deposits of them. The issue is that mining, and even moreso, refinement, are destructive to the environment. So, our minerals tend to come from less savory places who are willing to destroy their local environment to refine them. (There is no cost-effective way with our current technology to refine greenly.)

However, there’s plenty of cobalt in space and we can refine minerals in space too. In fact us humans can do it, right now, with all available technology, if it just weren’t so freakin expensive to get projects off the ground. This is why the US is subsidizing R&D on space flight actually, to bring the cost down so we can actually form a space mining industry.

There is no good reason whatsoever for a spacefaring civilization to mine planetside. It’s so expensive and the cost of launching things off a planet is astronomical. There are higher concentrations of rare minerals in asteroids everywhere you go. In Stellaris, planetside mining isn’t realistic at all, really! If this were real life, there is no logical reason whatsoever to not get most of your mineral needs from asteroids.