Can Amazon by Codisto import my Amazon listings and create products in Shopify?
No, Amazon Channel uses your online store product catalog as the 'source of truth' to sync with Amazon. Hence the products must exist in Shopify first. There are 3rd party importer tools available to create products in Shopify (search Google or app store) from your Amazon listings if you don't have products for these. You can then use Amazon Channel to create/link & sync your Shopify products with Amazon.
There are many reasons Codisto uses your ecommerce platform as the source of truth for product data. For example, It's much easier to update products in bulk via CSV import into Shopify than it is to update listings on Amazon directly. Also, it's better to maintain all product data in a single location that's not on Amazon because if anything goes wrong with Amazon it's possible to lose all your data.