React Native Dropdown Picker Category

I am a complete beginner and I am building an inventory app in react native. I came across this external library called Dropdown Picker. I managed to make it work but I just want to ask how can I include categories?

For example:

I want to have two dropdowns; one for category selection and one for specific item selection

I can’t seem to comprehend what is said on the docs because it only says to include a parent property to use categories. I want something like when the first drop down (for category) is given a selection the second dropdown (for specific item) will display the category’s children./

Thank you! Have a great day!

    export const items = [
  { label: "Cement", value: "cement", parent: "form_works" },
  { label: "Steel Rebar", value: "steel_rebar", parent: "steel_works"  },
  { label: "Coco Lumber", value: "coco_lumber", parent: "form_works"  },
  { label: "Sand", value: "sand", parent: "masonry_works"  },
  { label: "Gravel", value: "gravel", parent: "masonry_works"  },
  { label: "Plywood", value: "plywood", parent: "form_works"  },
  { label: "Concrete Mix", value: "concrete_mix", parent: "masonry_works"  },
  { label: "Paint", value: "paint", parent: "architectural_works"  },
  { label: "Nails", value: "nails", parent: "form_works"  },
  { label: "Bricks", value: "bricks", parent: "masonry_works"  },
];