It sounds like you would like some custom programming to create a portal that would allow you to read/update cs-cart and send info via other 3rd party apis. It would take knowing the api's of all your other 3rd party providers/vendors. And yes, you could use cs-cart as the "hub" for all that activity.
Question is: how knowing these APIs, considering these systemes are foreigners, regardless which side we look at it.
Most API's are documented. You'll need to reach out to the vendor of each. Assuming you've already reviewed cs-cart's api (https://docs.cs-cart.com/latest/developer_guide/api/index.html). For others, you'll have to investigate. But whatever developer you choose will need that collection of info to give you a reasonable quote on building a portal for you.
Hello, I apologize, I've never seen your answer; too much people does'tn answer on this forum. In your case, what do you need for evaluation ? I'm not specialist. Thx