Sidekick: Add Checkout Upsell Offers

Help me add upsell offers to my Shopify checkout:

Store niche: [YOUR STORE NICHE OR PRODUCT CATEGORY]
Average order value: [CURRENT AOV]
Target AOV increase: [DESIRED PERCENTAGE OR DOLLAR INCREASE]
Products to upsell: [LIST 3-5 PRODUCTS OR CATEGORIES TO RECOMMEND]

Please set up checkout upsells with these specifications:


  
    Upsell placement - Add product recommendations after the shipping method step but before the payment step. This is the ideal moment when customers are committed but have not yet paid.
  
  
    Product selection logic - Create rules that recommend complementary products based on what is already in the cart. For example, if buying [MAIN PRODUCT CATEGORY], suggest [COMPLEMENTARY CATEGORY]. Keep recommendations to a maximum of 2 items to avoid overwhelming the buyer.
  
  
    Offer formatting - Display each upsell with a small product image, the product name, a one-line benefit statement, the price, and a single “Add to order” button. Show the percentage saved if offering a discount.
  
  
    Discount incentive - Offer a [DISCOUNT PERCENTAGE]% discount on upsell items to encourage adding them. Make the discount visible with a strikethrough original price.
  
  
    One-click add - Ensure customers can add the upsell item without leaving the checkout flow or refreshing the page. The order summary should update instantly.
  
  
    Performance tracking - Set up tracking to measure upsell acceptance rate, additional revenue generated, and impact on overall conversion rate.
  
  
    Mobile display - On mobile, show upsells in a compact horizontal scroll or a single stacked card to save screen space.
  


Recommend the best Shopify app or checkout extensibility approach to implement this.