Yes, you understood it very well. The best way to proceed is to use a standard measure, which is life cycle analysis. This measures the carbon intensity of each molecule that goes into a final product. If you use green hydrogen made from biofuels and not grey hydrogen, which is traditionally used, that will affect the final value of the product and its carbon intensity. In my opinion, using a single standard is the best way to do it.
On April 30th, 2021. See this statement in context.