Add more features to my web application

I have a web application project in html, css, flask, python where the local sellers can signup, create their shops and manage inventory, as well as connect with other sellers. it is a kind of b2b marketplace for sellers. I want you to add a proper inventory management system to this web application so that sellers can manage their inventory and list the products on the site and also the chatting feature so that sellers can send friend request to each other and chat with each other.