You could build anything with Goaddon. Feel free to read through our project ideas. Some could be usefull for your ecommerce company, others could be offered to ecommerce companies by you as a service provider.
Purchasing products from suppliers is a business process that varies between online shops.
Still there is a pattern. The purchaser needs to be informed about sales volumes and stock quantities. And the purchase needs to be communicated to the supplier.
You could build an app that helps making purchasing decisions and communicates them to the suppliers.
By subscribing to the Goexplore addon you get a website that online shops can use to sign up.
By subscribing to the Gofetch addon you enable the merchants to import their orders and products into your database.
If you install the explorer-at-goexplore repository, your website even get a products page that you can add your buttons to.
So by now you have a website where a shop can sign up and enable the recurring import of orders and products into your database.
On top of that you need to build functionality to determine what products should be purchased, and from who. For that you need to integrate external data sources such as inventory and prices of suppliers.
This kind of project could be approached from many different angles, all of them quite complex.