While viewing your storefront in a browser, navigate to the integrated JavaScript console; for example, Google Chrome's Console. Use it to run the following code after entering your API token in the authorization header, and adding a valid Product ID for the entityId:

fetch('/graphql', {
        method: 'POST',
        mode: 'cors',
        headers: { 'Content-Type': 'application/json',
                 'Authorization': `Bearer token`},
        body: JSON.stringify({
            query: `
            query SingleProduct {
                site {
                  products (entityIds: product ID) {
                    edges {
                      node {
                        id
                        entityId
                        name
                        prices {
                          price {
                            value
                            currencyCode
                          }
                        }
                      }
                    }
                  }
                }
              }`
            }),
      })
      .then(res => res.json())
      .then(res => res.data);