Actually, the uses you mention are but a small fraction of the amount of hydrogen that is produced in the refining and petrochemical industries. Refineries use hydrogen to upgrade crude oil base stocks to high quality components of gasoline and diesel/jet fuels, as well as removing sulfur from those fuels for air pollution control. The petrochemical industry uses H2 to make fertilizer, plastics and a whole host of other products. You are correct, that most of it is done by cracking methane, with the resultant release of CO2 to the atmosphere. This is referred to as “gray” hydrogen. It is by far the largest volume of H2 produced. It is also produced at the site where it is utilized, so there is little or no transportation issues involved. The so called “blue” and “green” hydrogen touted by environmentalists is usually produced by electrolysis of water through a couple different processes. That is the hydrogen intended as a fuel source for future vehicles and aircraft - either through fuel cells or direct combustion.
The production and handling of hydrogen is well known and has been around for over a century. The problem is that both blue and green hydrogen are bing produced in relatively small quantities and are generally not manufactured where it will be used. So, a transportation infrastructure has not been developed to handle the volume of gas needed for the future. This issue could be addressed in one of two ways: 1) Produce the hydrogen at a remote site close to an electric power station and then pipeline the gas to the consumption point where it will be liquefied for use in the vehicles. 2) Produce and liquefy the hydrogen on-site, avoiding the need for the pipeline system. However, option 2 requires having ready access to the power grid at a point where the lines can handle the large amount of electricity needed for the generation and liquefaction of the hydrogen. This may require installing additional high voltage lines dedicated to the end use. Either way, a significant investment in new infrastructure will be required before the so-called hydrogen future can arrive. Building the airplane to use the hydrogen is just the tip of a large, and very expensive, iceberg.