Having experience in building Full-stack Hybrid(iOS and android) Mobile applications using Expo or React Native, Can be using real-time databases like firebase and also with Backend as Express and MongoDB. You can get a full web app and Mobile app keeping the same backend for both.  Provide you with the best(ie. maintaining the trade-off balance for security and cloud at its best) available solution.

Depending on the service you want we can negotiate.

The below explanation is for techies.

All the above-mentioned skills are full-featured like having REST API and Redux for state management

JWT authentication and token system and session management and great Navigation feature from RN5.