Currently, it looks like there isn’t an option for configuring how many items (amount) can be added to an order.
It would be nice to have an option to say like: “Per order, only 10 soups are possible (due to logistic/delivery reasons)”.
Or maybe to restrict the total amount of items for an order.

    Not quite - this is per order and I’m guessing at the point of adding to the cart. You would be best to write a custom extension to do it.