This is an interesting consideration as, once again as a pencil (and a Bic pen, and fountain pen) user myself, I have always wondered what was worse between cutting trees (or reusing hemp, which is a also a plant) to make the casing, or reusing some sort of already wasted material instead of throwing it away.
I mean that very seriously as all techniques do require a lot of energy to get to the result they want to achieve. That energy is to me the real ecological issue: the one that is costing less energy should be favorited.
Personally, I much prefer wooden pencils there is not the hint of the beginning of a doubt about that (and I pay good money to buy quality ones) but I would change and get rid of my 'preference' in a heartbeat if there was data showing something else was a better choice energy-wise. Be it recycled plastic, or cannabis, or that really interesting & intriguing concept showcased in the OP.
Thank you. It's your 'FFS' that triggered the whole discussion ;)
The answer should also take into consideration the place of extraction/growth of the raw material (and the cost of getting it and storing it, using whatever tools are required), its shipping to the pencil manufacturing plant, how it should be handled and processed maybe. And a few other things like that but, yeah, I would not be surprised if plastic was not the best choice there was.
I would not have thought about asking AI myself because, well, I'm not much into using them. partly because, I don't like the world their owners are trying to make a reality, partly because they consume so much energy.