How to Add an Is This a Gift Checkbox to the WooCommerce Product Page

/** Show an "Is this a gift?" checkbox before the Add to Cart quantity field */
add_action( 'woocommerce_before_add_to_cart_quantity', 'render_is_gift_checkbox', 35 );

function render_is_gift_checkbox() { ?>
    <p class="is-gift-wrapper">
        <label class="checkbox">
            <input type="checkbox" class="woocommerce-form__input woocommerce-form__input-checkbox input-checkbox" name="is_gift_purchase" id="is_gift_purchase" value="yes">
            <span>Is this a gift?</span>
        </label>
    </p>
<?php }

add_filter( 'woocommerce_add_cart_item_data', 'store_gift_flag_on_cart_item', 10, 2 );

function store_gift_flag_on_cart_item( $cart_item_data, $product_id ) {
    if ( isset( $_POST['is_gift_purchase'] ) && 'yes' === $_POST['is_gift_purchase'] ) {
        $cart_item_data['is_gift_purchase'] = 'yes';
    }
    return $cart_item_data;
}

add_filter( 'woocommerce_get_cart_item_from_session', 'restore_gift_flag_from_session', 10, 2 );

function restore_gift_flag_from_session( $cart_item, $values ) {
    if ( isset( $values['is_gift_purchase'] ) ) {
        $cart_item['is_gift_purchase'] = $values['is_gift_purchase'];
    }
    return $cart_item;
}

add_filter( 'woocommerce_ship_to_different_address_checked', 'auto_open_shipping_for_gift' );

function auto_open_shipping_for_gift( $checked ) {
    foreach ( WC()->cart->get_cart() as $cart_item ) {
        if ( isset( $cart_item['is_gift_purchase'] ) ) {
            return 1;
        }
    }
    return $checked;
}

add_filter( 'woocommerce_checkout_fields', 'rename_shipping_heading_for_gift' );

function rename_shipping_heading_for_gift( $fields ) {
    foreach ( WC()->cart->get_cart() as $cart_item ) {
        if ( isset( $cart_item['is_gift_purchase'] ) ) {
            add_filter( 'gettext', function( $translated, $original, $domain ) {
                if ( 'Ship to a different address?' === $original ) {
                    return 'Who is this gift for?';
                }
                return $translated;
            }, 10, 3 );
            break;
        }
    }
    return $fields;
}