You can sell many different products with the same pixel. For example, some of the general stores that advertise massively like Vigoshop.pl have just 1 pixel. So it’s ok to have few products and sell them with 1 pixel. It’s ok to have 1 pixel for multiple products. I overall recommend focusing on 1 product whenever possible so if you have 1 product, you can definitely go with 1 pixel and have no issues. Then find another product in a similar niche and scale it using the same pixel. This way you are maximizing the learning process.