The short answer is no, custom products (that is products you've created in your inventory as opposed to importing from our catalog) will not sync to Amazon.

Further explanation below:
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In order for the condition variant to properly connect to the Amazon marketplace, there has to be a SKU attached to that variant. This "SKU" isn't the manufacturer SKU, but rather a unique value generated by our catalog that is attached to each condition of each product.

Because the SKU is generated by our catalog, only products imported from the catalog can sync between CC admin and Amazon. Any custom products created in the inventory in the admin can't currently have variant SKUs, and won't be listable to Amazon.