It would be interesting in future to add a P2P type of Protocol to let users create P2P Escrow Contract for Secure Transactions where the 2 accounts need to sign to release funds.
A perfect Example is Binance with Their P2P Marketplace for Crypto to Fiat between Users... This could also handle Real World Sells, where the Buyer and Seller dont trust each other, similar to Real World Marketplaces like Alibaba "Trade Asurance"where you can dispute
The Final Decider in case there is a Non Resolved Conflict should be the Designed Marketplace Owner...
As aditional Feature, a Simple Chat Messaging System between Wallets Accounts could help Users to Comunicate. but this is not needed for Firsts Iterations of the Product