Ann: Hazer Secures Significant Milestone in IP Protection Rights, page-34

You can find this paper at a certain Sci(ence) Hub. https://www.sciencedirect.com/science/article/pii/S2238785420314733

Therein they outline a process that uses some extra hydrogen (see section 3.2) where they're using argon as a carrier gas to help generate the plasma, but they have to add extra hydrogen 1 to 10 parts methane to get the graphene morphology.

So it uses a lot of energy and needs some extra hydrogen to change the plasma to create graphene specifically. This suggests to me that, at least this version of plasma pyrolysis is restricted to the size of a chamber that could create the plasma, and it is more conducive to graphene production than high volume hydrogen production. I am not an an expert though so take what I say with appropriate caveats. DYOR.