How to render a dropdown box with nested array?

[cngx4444]

I am trying to render a dropdown box with nested array. My Question is how to implement rendering ?

How to show the selected value?

     Selected Value:
     {`fields.${parentFieldIndex}.props.${index}.value`}

As I cannot get the current selected value in option, I can't render the button here.

function handleChange(event) {
  if (e.value === "first") {
    setShow(true);
  } else {
    setShow(false);
  }
}
        
{showBtn === "true" ? (
        <div>
          <button type="button">Button</button>
        </div>
      ) : null}

Expand snippet
Expected result: If user selected "first" option, the sub list option will show the Button.

Here is sample code: [https://codesandbox.io/s/naughty-pasteur-59lyrs]