A conversion-focused upsell section designed to boost Average Order Value (AOV) by encouraging customers to replace their selection with a premium or upgraded product model, featuring a high-contrast side-by-side comparison layout showing base and premium versions, dynamic price differences calculations with clear upgrade savings labels, variant selections and comparative feature highlight lists, and a frictionless AJAX CTA button to swap the base version in the cart with the upgraded product, fully scoped under a parent ID to ensure conflict-free execution.