In the “smaller vehicles” part, great obstacles need to be overcome.

I would be content with doing only the parts that are reasonably economical and efficient:

• produce it, store it as a compressed gas
• if CO2 is available, convert it to methane (can be liquefied for distribution) or even bigger molecules
• if there is demand, use it to reduce steel
• if storage maxed (no CO2, no ore to reduce) burn it back to water in a turbine, selling electrical power when the market needs it

Economically, this would likely make ends meet - and keep hydrogen away from consumers (consumers are careless and their systems often faulty, while hydrogen is demanding and dangerous).