Our research aims at supporting existing therapies for children with intellectual and developmental disabilities (IDD) and with autism spectrum disorders (ASD). The personal and social autonomy is the desired end state to be achieved to enable a smooth integration in the real world. We developed and tested a framework for storytelling and learning activities that exploits an immersive virtual reality viewer to interact with target users. Our system uses Google Cardboard platform to enhance existing therapies for IDD and ASD children, enabling caregivers to supervise and personalize single therapeutic sessions. This way curative meetings can be adapted for each child's specific need accordingly to the severity of their disabilities. We co-designed our system with experts from the medical sector, identifying features that allow patients to stay focused on the task to perform. Our approach triggers a learning process for a seamless assimilation of common behavioral skills useful in every day's life. This paper highlights the technologic challenges in healthcare and discusses cutting-edge interaction paradigms. Among those challenges, we try to identify the best solution to support advanced visual interfaces for an interactive storytelling experience. Furthermore, this work reports our preliminary experimental results from a still ongoing evaluation with IDD and ASD children and discusses the benefits and flaws of our approach. On the one hand, we explore children reaction to - and acceptance of - the viewer, on the other hand, therapists' ease of use when interacting with our framework. We conclude this paper with few considerations on our approach.