Background: Why promising health technology ventures stall between product development and real-world deployment remains insufficiently explained in entrepreneurship research. Market-centric models emphasize experimentation, customer discovery, and product-market fit, but these mechanisms are less explanatory where access to users, clinical settings, and procurement channels is institutionally mediated. Methods: This study develops a process explanation of venture progression in regulated health innovation settings. Drawing on institutional theory, innovation systems research, and process views of entrepreneurship, it uses a longitudinal comparative case design to analyze early-stage health technology ventures in Rwanda over an 18-month observation window. The empirical material comprises venture milestone plans, periodic progress reports, observational notes, and documented interactions with regulatory, clinical, and institutional actors. Results: Venture progression was not explained primarily by technical capability, entrepreneurial effort, or early market interest. Rather, outcomes varied according to whether ventures achieved coordinated validation across interdependent regulatory, clinical, and institutional domains. Three recurrent pathway configurations were identified: sequential alignment, associated with forward progression; temporally constrained alignment, associated with delayed progression despite coherent sequencing; and fragmented progression, associated with stagnation. The findings show that legitimacy in regulated health innovation settings is multi-domain, threshold-based, and time-dependent. Conclusion: The study advances the concept of coordinated validation under temporal constraint to explain how ventures move, or fail to move, from development to deployment when market entry depends on synchronized institutional approval. It contributes to entrepreneurship and innovation theory by reframing venture progression in regulated environments as a coordination problem rather than a pure capability problem. Rwanda serves as a revealing case because its comparatively coordinated health system makes the underlying synchronization problem especially visible.