Hi,
It sounds like you want to display product details, including quantities, directly in the Sales Order List view and also ensure that this information is available in the Pivot view for analysis. You're right that the sale.order.line is the model that holds the product and quantity information, but typically this isn't directly accessible from the sale.order model in list views.
You can add a related field in the sale.order model that pulls data from sale.order.line. However, the challenge is that a sale order can have multiple lines, so displaying multiple product names and their corresponding quantities needs some customization.
Add a custom compute field in the sale.order model to gather the products and their quantities from the sale.order.line model. This will make the information available in the list and pivot views.