wow, some people talking in this thread as if Magnate Lords mod didn't exist.
People there are MODS that add goods to counties. It's not that complicated.
The complicated thing would be adding actual shipments of actual goods instead of just abstracting the trade itself. But if you at least added goods you could add things like lowering revolt risk for counties connected through a merchant republic to certain trade goods, or expand supply capacity in the province, or increase levy, etc.
People there are MODS that add goods to counties. It's not that complicated.
The complicated thing would be adding actual shipments of actual goods instead of just abstracting the trade itself. But if you at least added goods you could add things like lowering revolt risk for counties connected through a merchant republic to certain trade goods, or expand supply capacity in the province, or increase levy, etc.