To add a product in addition to the default Prestashop method, there is another way to do it:
Create a product with POS-TPV
POS-TPV allows you a simpler and faster way. The product is created from the cash register itself and only by filling in the name and price it is possible to create a product.
Inside the POS Store. In the upper right menu button, you can create a new product.
It is also possible to create a complete product with all your information if you wish.