There is no off the shelf integration. Developers from the client's BP and the third party application (Shopify) will need to build the integration using development tools inbuilt in Sage X3. see link below:

Web services integration | (sageerpx3.com)

By Any chance to do you know any certified developer agency who can help us with that? 

Hi Haris, our company has developed a connector between Sage X3 and Shopify.

Please email me if you would like to discuss this further. [email protected].

Hi Haris, our company has developed a connector between Sage X3 and Shopify.

Please email me if you would like to discuss this further. [email protected].