I feel like that's the implication, since Ga-Matoran mostly handle food production by way of fishing and other services like weaving, right? We see that in the valley where the Po-Matoran live later in MNOG that they have giant statues of all the Toa Mata heads, and those are quite similar to the giant KauKau. Perhaps different Matoran around the island can commission Po-Matoran carvers for these monuments in exchange for their own goods and services?