@whaleross granular activated carbon for fish-tank filters is relatively less expensive - though you might be able to make your own charcoal with a fire-pit and have as effective material. Your stove hood filter probably has some kind of metal-framed and non-serviceable assembly - which could maybe be disassembled and "refilled". My vent hood filter appears to be a black piece of felt - questionable whether it actually contains carbon or not, tbh. I'd probably eventually replace it with metallic mesh in a multi-layered arrangement and not worry about carbon at all. The main role is to trap grease, not odors.

@PotentiallyAnApricot well if you already have some "wet" grease, I would not go look for graphite. They will work together, (see https://www.crcindustries.com/moly-graph-174-extreme-pressure-multi-purpose-lithium-grease-14-wt-oz/) but since there is already some wet grease there, a little more is just as good as adding something else, imho.