On the topic of City Package and Unpackage

[UWHabs]

NO IT IS NOT how the world worked for most of history.

The limitation on which 'units' or weapons a given army/society used was never based on what resources they had unless the resource was completely unavailable anywhere in their world, and the only example of that was the Horse, which went extinct throughout the Americas and thus was completely unavailable to any society there.

But in Eurasia, horses once domesticated were spread from Japan to Ireland, over mountains, across seas and straits, to any spot they could physically survive and breed (which left out only tropical Africa, where no large animal not immune to the tsetse fly could survive)

It works in Civ because Civ has always treated resources as immoveable, when in fact any animal or vegetable resource is very moveable and by modern times virtually infinitely moveable, But, and this is the important part:

Fixed Resources is a GAME MECHANIC only, and one that warps most of the game into artificial patterns and strategies.

The answer is not to argue about how to deal with an artificial game mechanic, it is to change the ^%$#@& game mechanic so that in-game you can actually play a semi-historically based narrative, not an artificial fantasy narrative based on static resources and their consequences.

Movable resources would be a little tough, always hard to balance anything and avoid a case of you just "planting" a bunch of horses. I've always viewed the resources too not necessarily as being the only places in the world that those resources exist, but just territory that is particularly valuable for that resource. Like you can make wine in the Okanagan region in British Columbia or in the Niagara valley in Canada, but neither of them would be a "wine" resource. That would be limited to your Bordeaux, maybe Napa Valley, etc... The truly special ones. Same with iron deposits - those aren't the only places you find iron, but spots where there's a particularly abundant or quality.

When you think of it that way, then the civ 7 model makes a little more sense. Empires all over the planet would have used some combination of iron or copper for their weapons through history, but if you live in an area with a higher quality iron deposit, then you have better iron for your swords so maybe you have a slight edge in battle. It's not like you just can't find something you can fashion into a sword so you're just going to give up trying.

Modern resources like oil, coal, rubber, etc.. are probably the slight exception, it's not like you can swap out and use like a steam powered tank and come close to someone burning oil in it. I'd be more inclined for the modern era to have resources actually gate-keep some units, which would also be another way the modern era gets spiced up fighting for resources.