User Mental Models of Security and Privacy in Connected Home IoMT: Implications for Interoperability and Governance

The Internet of Medical Things (IoMT) is increasingly used in connected homes. These medical devices share networks and ecosystems with consumer Internet of Things (IoT) devices. Matter is a consumer IoT standard, focusing on interoperability and technical security for smart-home devices. U.S. Food and Drug Administration (FDA) regulations for medical devices address safety, clinical validation, and compliance. Yet it remains unclear how these approaches apply to security, privacy, and governance in home IoMT adoption. We conducted scenario-based interviews with 40 participants (20 aged 18--30 and 20 aged 60+). Participants evaluated Matter-related features, including rapid over-the-air updates, local-first connectivity, and ecosystem integration. They also considered FDA-related expectations for tested updates, clinician-oriented connectivity, and cautious integration. Participants valued accuracy, transparency, and simple control, but did not want responsibility for complex configurations. They preferred slower, well-explained updates for safety-critical functions and context-aware connectivity with more sharing during emergencies. They also preferred selective integration that enables emergency access without broadly exposing household data. These results show that user mental models and risk tolerances can diverge in important ways from both current IoT standards and medical device regulation. Future home IoMT designs should support user-centered interoperability, security, and data governance.