If you have natural gas connection, you can be charged for both kWh and GJ on the same bill!

Or your utility may use freedom units like Therms

Ccf is also common because it's the directly measured quantity by your gas provider and you don't need silly charts like https://www.eia.gov/totalenergy/data/monthly/pdf/sec12_5.pdf

Seems odd to sell a gas by volume though... are these understood to be at a standardized pressure/density?

My gas bill each month lists the correction factor used for that month to compensate the meter reading to the volume consumed (and thus billed) based on the average weather.