I've been doing a lot of research on different e-commerce checkout processes to match my clients needs and basically he is looking for a configuration where you add items to the cart and then upon viewing them on the checkout page are given the option to customize the product. In this case it would be the option to add a monogram to a towel.
Site for reference is: https://schweitzerlinen.com/classic-800
There you can add the towel to the cart, then proceed to the cart page and add the monogram to it before going to 'checkout'. I tried running a query for this example site on http://builtwith.com/ but it could not identify the shopping cart platform used. I tried to reach out to them also and am waiting to hear back from their developer.
Now I have already seen extensions to add product customization that are very in-depth but they all are used on the product page, not checkout.
I have experience in developing/customizing templates/themes for Bigcommerce and Magento however I have limited experience in advanced customization of extensions for those platforms.
Essentially I'm just looking for some suggestions on at least a starting point to build upon. My client is open to other platforms besides Bigcommerce and Magento as long as a similar result can be achieved like on Schweitzer Linen.
I'd appreciate any guidance or insight if you've seen a similar checkout experience, thank you!