Accessing nested json data with Hooks

I am having trouble filtering the json that I have in React Typescript Using Hooks.I have a JSON that comes from a fetch and it looks like this:

[{"dealer 1":    [    {"name": "SERVICE 1""city": "NORTH CANTON""phone": "3306596372""isOpen": "true"    },    {"name": "SERVICE 2""city": "OHIO""phone": "3306596372""isOpen": "true"    }    ]},{"dealer 2":    [    {"name": "SERVICE A""city": "WASHINGTON""phone": "3306596375""isOpen": "true"    },    {"name": "SERVICE B""city": "SEATTLE""phone": "3306596376""isOpen": "true"    }    ]}]

my code for fetching the api is:

useEffect(() => {    axios.get("API URL here")        .then(res => {            console.log(res)            setCTSN(res.data)        });}, []);

and I wanted to return all open dealers so I need to filter it by "isOpen=true"

const isOpen = 'true'const result = OPEN    .map(item => ({        ...item, //Spread types may only be created from object types.ts(2698)        children: item.children            .filter(child => child.value.includes(isOpen.toLowerCase()))    }))    .filter(item => item.children.length > 0)console.log(result)

but I am getting an error with the '...item' and I'm not sure if I am doing it correctly in React Typescript.

Can someone help me?