Of course I mean the content accessible through the link, not comments like on An alternative method to tap high altitude winds [by producing a lifting gas at altitude] topic (where the link comes from) or the previous one.
“Envisage” does not mean “make”. Some people in companies think about hydrogen as a condition for the return of airships, and production on board can be a decisive point. A project is on
https://trimis.ec.europa.eu/project/multibody-advanced-airship-transport
Some examples of companies making prototypes of solar-powered airships: