Yes there is a real working actually decentralized P2P marketplace particl.io all transactions mandatory ringct for maximum privacy, built on latest BTC codebase so atomic swap capable. There is a swap Bot in the wallet that allows you to swap BTC to PART directly without needing another 3rd party app though in the future we will have the atomic swap option which is exciting and can't wait to see this implemented. you can check out live listings here without downloading the software https://www.demarkets.io/particl/explorer this site broadcasts listings from the software it is not the market. the market is software you need to download it here is a guide https://particl.wiki/tutorial/market/start

Oh! and "without any doubts of being scammed." we have you sorted here also as Particl uses a double deposit escrow aka MAD escrow or Mutually assured destruction escrow, seller has no incentive to rip you off as you can just refuse to release payment + security deposit if package not arrive. you also have no incentive to rip him off because he can refuse to release your security deposit. this keeps all actors as honest as humanly possible within a decentralized environment. future releases will include adjustable escrow and dispute settlement but right now it's just the basic MAD escrow.. but it works have used it a lot over past months.