I am working on a game with supply lines. Basically resources are local and you have to work from stockpiles. So you place a foundation indicator with a stockpile. Then you have to physically move the resources in a unit to the foundation. But you can build in spurts and resources are spent over time so you don't need it all at once. And you also have some economics and moving weapons and armor to barracks and armories and so forth.
And you do indeed need to decide where to produce, and not only units, but do you process resources and create items on site of raw material gathering or do you ship it to a city. It would certainly be interesting to see how smart players are at dealing with those decisions.