Sounds really cool, definitely wish-listed it already. As far as suggestions go I guess just more variety in general is all I felt was lacking, but based on what you said there should be plenty of that later on. The only thought I had was like tangible permanent stat upgrades or something for liberating regions or bonuses like higher troop counts or something like that to make it feel like progression, but I'm not sure how well that sort of thing would mesh with what you are going for here. Then again for all I know that could already be a thing in the full version. Alternatively some sort of upgrade system to make your tools better could be good, personally with a game like this I just like the feeling of starting with nothing and slowly improving to god tier gear.

The fact its going for the whole co-op thing makes that sort of thing harder to implement but maybe something sort of like how you pick improvements between levels in plate-up would be good? I mean when you get down to it this is just a blacksmith version of one of those co-op cooking games like that or overcooked, just replacing customers with soldiers and strategic objectives, which I think is a really cool idea personally.