As satellite-based navigation moves toward next-generation resilient positioning, integrating emerging LEO-PNT signals with existing GNSS systems has become increasingly important. With growing challenges from urban environments, interference, and signal degradation, improving positioning robustness and reliability is critical. My research focuses on developing data-driven and AI-enabled positioning frameworks that combine LEO and GNSS observations with advanced channel modeling and sensor fusion techniques. By leveraging simulations, real-world measurements, and distributed learning methods, this work aims to enable robust and trustworthy positioning solutions. Ultimately, the research supports resilient navigation for future mobility, robotics, and safety-critical applications.