magento2 – Creating a vendor panel in magento 2?

I am new to magento, and I have got a requirement from client.

Background of requirement : There are 10 vendors pincode based and 4 main vendors zone wise, linked with my client. The client wants to route the order based on the nearest pincode vendor. The vendor can accept or deny the order received. Once the vendor denies the order, the order then goes to the main vendor of that zone. I know how to create custom modules but I am not sure how to handle this request and from where to start ?

How can I achieve this functionality and what are the aspects I need to cover in the order fulfillment under this scenario. ? Below are the major requirements on frontend :

  1. The user enters pincode, it is checked from backend and deliverable vendors are listed along with their price list.

  2. Once user selects a vendor and places an order the order is routed to that vendor.

What all will be the tables I need to consider to create module to achieve this requirement. Is there any similar extension for this ? I tried searching for multi vendor module but that seems little different or can I use the same and extend it, can anyone guide me by giving some idea as I have just started learning this framework.