Hello

I searched the web looking for help for configuring odoo as a market place and could find only two solutions, one that relies on odoo configuration but is for v13 and does not seem to be possible with the latest version and another that uses an external module. 

Using an external module is out of question for me so I need your help please in that. My solution does not maintain any inventory so I want the system to automatically send new sales as purchase requests to the participating vendors asking them to do dropshipping to the client who made the purchase. I dont know if vendors need to be defined as companies or as vendors. I need vendors to be able to maintain their products but that is not an absolute necessity. And I need vendors to be able to see the new orders and process them. Card payment is not common in my country so we need to rely on cash on delivery. I need to have a subscription fee for vendors or be able to calculate a percentage of the total sales we made for them.