It has to be measured for each field. The fugitive emissions are...

It has to be measured for each field. The fugitive emissions are those lost along the way from field to sales, so really depends on quality of operator and regulators. Tends to be more in those small "ma and pa" US fields than say the more heavily regulated jurisdictions.
Then there's the field itself, and CO2 content which varies considerably.

But plenty of low CO2 fields to choose from.

While that helps tap into those various standards and associated incentives, the key in the end is still to reduce emissions. So converting methane to hydrogen and graphite is still a big gain compared with using methane directly regardless of co2 content or fugitive emissions. It's not like we can turn that energy source off overnight so even the less clean options are great during the transition.