Sheet rock isn’t very green. It requires a lot of heat to make it and the ingredients are not great. I’ve had little luck finding sheet rock alternatives. Plaster and lath is one but the labor costs make it hard to compete with sheet rock. The best I do so far is use salvaged sheet rock.
Here is a list with some options. I’ve not looked into them since it will be hard to beat the cost of salvaged sheet rock. But when the time is right I will. In the long term it makes a lot of sense.