I didn't want to use metal brushes and scratch the cajon face. Nylon wasn't the sound I was looking for.
I had been exploring Etsy and found these Natural S. African Grass Drum Brooms sold by JKingPercussion.
Love the brooms! Quality workmanship. Great sound.
They're heavier than I thought they'd be, but that's good! The extra weight seems to bring out the bass more and the broom grass has a really nice sound when "stirring".
I have not tried them on djembe yet.
5 stars and I highly recommend them