Is it possible with a Shopware App (not a plugin!), to forbid certain products?
Example: I'm selling stuff with shipment in small stuff (DHL/UPS) and big stuff, with "your own truck" and I don't want to mix this in one order.
There is no event "product add to cart", so is there any possibility to throw an exception if the customer adds a certain product, based on the products already in the cart?
This should be doable with App Scripts. Here is the documentation about removing line items from the cart.