You could try Sulfasalazine, it modulates prostaglandins lowering pgd2 and increasing pge2.
Adenosine is better than caffeine from what I heard. Caffeine is also pretty much considered as cox2 inhibitor, being bad for pge2.
Adeno also has the hair thickening effect like niacinamide, and the powder form is cheap dirt( I checked recently ebay, one seller from australia was selling it). I am not sure about peppermint oil, no one had success with it and there is contrary research showing that it either increases or inhibits pge2. I would guess it is the second considering no one has that success of the mice study.
Maybe also try some vitamin c serum. Vit C reduces Dkk1. You could get a Vit C serum with argan stem cells. Argan stem cells have shown to increase Sox2. In theory Sox2 is also beneficial for hair. I am thinking of getting one for myself.