You want to make the buying experience as easy as possible for your viewer.
When you choose a landing page for your ad, consider how many clicks it takes for the customer to successfully purchase your product. How many words and numbers will the customer need to type to complete the transaction? The less work it takes a customer to buy a product, the more likely they are to complete it.
Test your landing page yourself! See how many clicks and keystrokes it takes to buy your own product. Make that number as low as you can to really maximize sales on your Google Ads.