What are the uses of items like spices and chocolate. What do you even do with them?

Those were used for a previous festival, the winter festival, where different ingredients were used with spices, and in the right combination and amount, you get to make a pet.

Now that the festival is over, the spices and ingredients have no more use. The ingredients/spices are unlikely to be usable even if this feature returns with the next winter festival at the end of this year, but you might be able to sell it for a bit of gold.