Internal Operations App Development

I'm looking to develop an internal operations app for my company, focusing specifically on project management. The primary function of this app will be to enhance our internal operations.

Key features required:
- Task assignment and tracking

Ideal skills and experience:
- Mobile app development (iOS and Android)
- Experience with project management tools and features
- UI/UX design for intuitive user experience
- Backend development for robust task management systems
- Knowledge of integrating collaboration tools

Please provide examples of similar work done, along with your approach and timeline for development.