Naturligt Snygg review for Shopify Checkout Blocks

I need to have the Plus plan and pay over 2 300 $ per month to be able to edit the check out page. The place for up sales. Most people skip the cart, where we can ad stuff. Why is it only free to edit thank you page and order status page? As a very small company it's so important with every cent saved and added in up sales. Please make it possible to edit check out even as a small shop owner. I already pay for so many apps for features that should be basic in Shopify.