Sure, you can do this with our premium add-on ATUM Export Pro.
With this add-on you will be able to export/import almost any kind of data in your site. In your case you can use the suppliers template to import the suppliers, and then the products template to assign the suppliers to the products and then import it to your site.
I leave you here the link to the documentation where you will find useful info about how it works: https://forum.stockmanagementlabs.com/t/atum-export-pro-documentation
And the link to the demo site in case you want to try the free trial: https://stockmanagementlabs.com/addons/atum-export-pro/