“Flutter AdMotors” application is the ready made complete classified platform application like Olx, Mercari, Offerup and Carousell but it is for only car niche. It is easy to setup and no coding required. It support for both iOS and Android by using single backend.

Demo: https://codecanyon.net/item/flutter-admotors-for-car-classified-buysell-ios-and-android-app-with-chat-10-/27210541