Plugin in CMS for Walmart orders to import orders and export shipping information, similar to Amazon.
Currently we're using a file method to communicate with Amazon (beta) and will transitioning off of that in favor of using their web services (AWS) that would allow CMS to communicate with Amazon directly without the use of files.
In a similar manner Walmart has functionality that allows you to upload and download orders in Excel from their Seller Center
or they also offer an API for direct communication
The latter is more complex and would require a dedicated CMS plug-in so that would be an option further down the road unless there is high demand for it. The Excel method, however, may be possible to work with sooner than later.
Let us know your Walmart order volume and get us a couple of sample order downloads from their Seller Center and we can advise on what your options are for optimizing the import/export.