Through the digging I've done, I haven't found a way to change max sockets per piece through datapacks or config. Is this possible to do, and if so, how?

Naturally rolled? Not currently, it's this hardcoded thing set in the loot rules of each individual rarity.

however, recipes for the addition of sockets define the max number of sockets that item can contribute to, so you can theoretically increase the max this way
https://github.com/Shadows-of-Fire/Apotheosis/blob/1.19/src/main/resources/data/apotheosis/recipes/superior_add_sockets.json#L11

ill look into it, thanks for the lightning fast response