LPG CYLINDER DELIVERY APP

I am looking for help creating a mobile app to be used on both Android and iOS platforms. The app will be an D2C app, which is meant to be used for the delivery of LPG cylinders for cooking and heating purposes. I do not have any designs ready, and I will need help with the designing of this app from scratch. Additionally, I need help with the backend development of the app as I am not experienced in software engineering. Therefore, I am looking for someone to help me create this app from the ground up, who has experience with both front- and backend development for mobile apps.