The “upgrades” are the OTO’s for the particular product. You can sell them as is, or you can create a sales funnel using them, this is what I do. I create a front end product and use the upgrade version for the one-time offers, which I then charge a higher price for.
All the OTO’s (One-Time Offer) are ideal for funnels. What happens is when someone purchases the FE (Front-end) they go to the upsells or commonly known as ‘sale funnels.’ This helps to make more sales and conversions.
One of the most important things to keep in mind… only every add additional products in the funnel that are related to the product the customer has purchased.