Abstract: Hydrogen has a high gravimetric energy density but an intrinsically low volumetric energy density under ambient conditions. Conventional hydrogen storage and transportation technologies based on high-pressure compressed gas or cryogenic liquid hydrogen therefore require substantial compression or liquefaction energy, stringent safety measures, and relatively expensive auxiliary equipment. Chemical hydrides provide an alternative route by storing hydrogen in stable chemical bonds at room temperature and releasing it on demand. Among these materials, sodium borohydride (NaBH₄) is attractive because of its relatively high hydrogen content, good solid-state storage stability, and established hydrolysis chemistry. Nevertheless, conventional liquid-phase NaBH₄ hydrolysis generally requires a large excess of water, catalytic components, liquid-handling devices, and product separation units, which reduce the effective hydrogen storage density and increase system complexity. To clarify whether vapor-induced hydrolysis combined with gas–solid ejector feeding can address these limitations, we evaluated the technical basis, performance potential, and major engineering constraints of an ejector-enhanced NaBH₄ steam-hydrolysis strategy for a solid-state hydrogen storage unit. A literature-based synthesis and parameter-comparison approach was adopted. The analysis focused on the evolution from liquid-phase to vapor-phase hydrolysis, the deliquescence–dissolution–hydrolysis mechanism of NaBH₄, the hydration state of sodium metaborate products, hydrogen-recirculation ejectors used in proton exchange membrane fuel cell (PEMFC) systems, and the transport characteristics of reactive powders. Accordingly, a coupled process is proposed wherein part of the generated hydrogen acts as the motive fluid of a gas–solid ejector, entrains NaBH₄ powder from a sealed hopper, promotes preliminary gas–solid dispersion, and conveys the powder to a steam-hydrolysis reactor, while the produced hydrogen is divided between the PEMFC and recirculation branch. The reviewed results showed that vapor hydrolysis is not a simple direct gas–solid reaction. When the ambient relative humidity exceeds the deliquescence threshold of NaBH₄, water vapor is absorbed by the particle surface, forming a concentrated liquid film; NaBH₄ then dissolves in this film and subsequently undergoes hydrolysis. Consequently, temperature, steam partial pressure, relative humidity, and the hydration number of the NaBO₂·xH₂O product are strongly coupled variables that determine reaction initiation, conversion, mass-transfer resistance, and practical hydrogen storage density.Compared with conventional liquid-phase hydrolysis, the vapor route can reduce the molar ratio of water to NaBH₄ from values typically >10 to approximately 2–6. Under suitable temperature and steam-pressure conditions, high conversion can be achieved without relying on a conventional catalyst, thereby reducing catalyst-related deactivation, separation, and recovery requirements. The gas–solid ejector offers a complementary system-level advantage. By using recycled product hydrogen as the motive fluid, negative-pressure powder suction, pneumatic conveying, and initial gas–solid mixing can be integrated within a component containing no rotating feeding mechanism that crosses the hydrogen sealing boundary. This configuration has the potential to reduce the number of mechanical seals and moving parts, improve compactness and system integration, and support load-responsive hydrogen generation. However, the coupled process also introduces critical engineering challenges, including powder agglomeration and deposition caused by moisture sensitivity, steam backflow toward the powder-storage section, backpressure mismatch between the ejector and reactor, insufficient motive-flow availability during transient or low-load operation, and fluctuations in powder delivery and hydrogen production. These issues indicate that ejector geometry, powder properties, steam distribution, reactor backpressure, and hydrogen recirculation cannot be designed independently. Overall, vapor-induced NaBH₄ hydrolysis coupled with hydrogen-driven gas–solid ejector feeding is a promising approach for compact solid-state hydrogen generation, especially where simplified sealing, reduced water inventory, and on-demand hydrogen supply are required. Future engineering development should prioritize quantitative gas–solid reaction kinetics, validated CFD–DEM models that incorporate particle transport and reaction, distributed steam-injection strategies that maintain a dry conveying zone and a controlled wet reaction zone, and closed-loop control coordinating powder feed, steam supply, buffer pressure, hydrogen recirculation, and PEMFC demand. These efforts are essential for translating the proposed coupling concept from literature-supported feasibility into a stable, efficient, and controllable solid-state hydrogen generation system.