Fifth, there are three Inca deities I find uniquely interesting:
- Huamancantac - God of guano (used for fertilizer)
- Urcuchillay - The rainbow-colored god of llamas, also believed to be the constellation lyra. According to legend, Urcuchillay drank water from the celestial river (the Milky Way galaxy) and urinated it onto Earth as rain.
- Axomamma - Potato goddess
Historically, guano is used as fertilizer but also as a key ingredient to create gunpowder. Maybe there could be a God of Guano that also functions as a god of gunpowder and agriculture. These portfolios are pretty different, so maybe they could be different interpretations of the same deity. Halflings could worship the Guano God as a god of agriculture while dwarves worship them as a gunpowder god. Tie in some connection to werebats or vampires for good measure.
What role do llamas play in your setting? This is probably the first time anyone has asked this question, but answering it could be fun. If halflings ride llamas, how do they feel about the llama god? Maybe they're also a god of travel or war? They could depict their war god as riding a llama. Or they could look like a weird llama-equivalent of a centaur.
I have never seen a D&D setting with a potato goddess in it. Now I want to play a Cleric that worships the Mother of Potatoes. She'd probably be a minor agricultural deity, but if a culture in your setting primarily feeds themselves off of potatoes, some people would probably feel very strong affection towards her. Maybe she could look something like a potatofied version of Argus from Greek Mythology, due to the "eyes" connection. Or
these Moche potato figures. Depending on how potatoes are used in the setting she could have a different portfolio. For example, if potatoes are often used to make alcohol she could also be considered the god of madness, like Dionysus. Or she could be a goddess of immortality if freeze-dried potatoes are one of the main sources of food for a culture.
tl;dr - The Inca were cool and your D&D setting should have a potato goddess.