First - why can't we use a sickle? Second why is water in a thermos able to fit in the water slot with a cooling effect for hours but coffee in that same thermos is a minutes only buff and ONE serving?
Make it like water for the water slot but give it the opposite effect of water. A warming buff exactly the opposite of the cooling effect water has.
And for the sake of all of Asgard, make it so you can harvest coffee, teas, etc, with a damn sickle.
As it is, I consider these drinks NOT worth any players time or effort.
It makes sense that the thermos with coffee or any other beverage would have 4 servings, then and only then it will make at least some sense. as it is now, a short-term insignificant buff just does not justify the effort expended.
I agree with the four servings as a minimum change, but I actually like the idea of the thermos being consumed just like a canteen. I actually think the canteen lasts way to long. So if you reduce the longevity of the canteen and allow thermoses to be consumed as water, that'd be great (and make sense).
I remove my canteen from my suit slot when in the arctic because it auto-consumes and causes extra cold; to the OPs point, a thermos in that slot should cause a warming buff when consumed.