You can still use methane as your hydrogen source for ammonia production if you do CO2 capture and storage when you produce the hydrogen. This is often called blue hydrogen, as opposed to green hydrogen from electrolysis and gray hydrogen from methane witgout CO2 capture and storage.

Most of the oil and gas companies are partly betting the farm on H2 from CH4 with CO2 capture and storage as a major source of energy in the coming transition, and thus a major source of profits for the next 30-40 years.