I think the first priority for you should be getting _something_ built and proving your core technology. But you are making it harder for yourself by adding more variables.

Natural gas is abundant in some areas and is wasted. If you can prove that you can build cost-efficient small-scale synthesis units, then moving to biogas should later be a no-brainer.

I'm also pretty sure that you need to pre-treat the gas to remove stuff like sulfur or ammonia from it. And you can get that for "free" in places that distill the LPG from the well gas.

From a "cynical investor" point of view, it looks like you're knee-capping yourself by going for a vastly smaller market. To me this is a huge red flag, usually pointing to companies that either do green-washing, or already plan to pivot once they get the initial investment.