Create a redirect in WooCommerce checkout based on applied coupon

Here is the flow:

1. Customer adds product to cart.
2. Customer adds coupon “smile” at checkout.
3. When customer places order the function will run before the Order
   Details page loads. Function will check for “smile” coupon and if it
   has been applied it redirects to a new page where they will be
   offered additional products for free. If not, then it continues on
   as normal.

I have been referencing two solutions I found through a Google search similar to parts of my problem. Individually I get them to work but together I cannot seem to get them to work correctly.

Here is my code:

add_action( 'woocommerce_thankyou' , 'sq_checkout_custom_redirect' );

function sq_checkout_custom_redirect($order_id) {

global $woocommerce;
$order = new WC_Order( $order_id );
$coupon_id = 'smile';
$applied_coupon = $woocommerce->cart->applied_coupons;
$url = 'https://site.mysite.org/score-you-win/';

if( $applied_coupon[0] === $coupon_id ) {
    echo "window.location.replace('".$url."');";
    } else {
    echo '<h3 style="font-size:200px; z-index:30000; color:#000 !important;">Coupon not applied</h3>';
    }
}

No matter what coupon I apply I get the message “Coupon not applied.” and no redirect happens.

The two solutions that I am referencing are:

Find applied coupon_id in cart

Redirect with JS

This code runs successfully:

add_action( 'woocommerce_thankyou', function ($order_id){
$order = new WC_Order( $order_id );
$coupon_id = "smile";
$url = 'https://site.mysite.org/score-you-win/';

if ($order->status != 'failed') {
    echo "window.location.replace('".$url."');";
}
});

And this runs successfully:

function product_checkout_custom_content() {

global $woocommerce;
$coupon_id = 'smile';
$applied_coupon = $woocommerce->cart->applied_coupons;
if( $applied_coupon[0] === $coupon_id ) {
echo '<span style="font-size:200px; z-index:30000; color:#red !important;">We are happy you bought this product =)</span> ';
} else {
    echo '<h3 style="font-size:200px; z-index:30000; color:#000 !important;">Coupon not applied</h3>';
}
} 
add_action( 'woocommerce_thankyou' , 'sq_checkout_custom_redirect' );