Add Custom Attribute To Recently Viewed Products Widget

here is the solution for overiding the controllers

Namespace/Module/etc/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
<type name="MagentoCatalogUiDataProviderProductProductRenderCollectorComposite">
    <arguments>
        <argument name="productProviders" xsi:type="array">
            <item name="sku" xsi:type="object">NamespaceModuleUiDataProviderProductListingCollectorSku</item>
        </argument>
    </arguments>
</type>
</config>

Namespace/Module/etc/extension_attributes.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
    <extension_attributes for="MagentoCatalogApiDataProductRenderInterface">
        <attribute code="sku" type="string"/>
    </extension_attributes>
</config>

Namespace/Module/etc/widget.xml

<?xml version="1.0" encoding="UTF-8"?>
<widgets xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Widget:etc/widget.xsd">
    <widget id="catalog_recently_viewed">
        <parameters>
            <parameter name="show_attributes" xsi:type="multiselect" required="true" visible="true">
                <options>
                    <option name="sku" value="sku">
                        <label translate="true">SKU</label>
                    </option>
                </options>
            </parameter>
        </parameters>
    </widget>
</widgets>

Namespace/Module/Ui/DataProvider/Product/Listing/Collector/Sku.php

<?php
namespace NamespaceModuleUiDataProviderProductListingCollector;

use MagentoCatalogApiDataProductInterface;
use MagentoCatalogApiDataProductRenderExtensionFactory;
use MagentoCatalogApiDataProductRenderInterface;
use MagentoCatalogUiDataProviderProductProductRenderCollectorInterface;

class Sku implements ProductRenderCollectorInterface
{
    /** SKU html key */
    const KEY = "sku";

    /**
     * @var ProductRenderExtensionFactory
     */
    private $productRenderExtensionFactory;

    /**
     * Sku constructor.
     * @param ProductRenderExtensionFactory $productRenderExtensionFactory
     */
    public function __construct(
        ProductRenderExtensionFactory $productRenderExtensionFactory
    ) {
        $this->productRenderExtensionFactory = $productRenderExtensionFactory;
    }

    /**
     * @inheritdoc
     */
    public function collect(ProductInterface $product, ProductRenderInterface $productRender)
    {
        $extensionAttributes = $productRender->getExtensionAttributes();

        if (!$extensionAttributes) {
            $extensionAttributes = $this->productRenderExtensionFactory->create();
        }

        if($product->getSku())
        {
            $extensionAttributes
                ->setSku($product->getSku());
        }

        $productRender->setExtensionAttributes($extensionAttributes);
    }
}

Namespace/Module/view/frontend/ui_component/widget_recently_viewed.xml

<?xml version="1.0" encoding="UTF-8"?>
<listing xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <columns name="widget_columns">
        <column name="sku" component="Namespace_Module/js/product/sku" displayArea="description-area">
            <settings>
                <label translate="true">SKU</label>
                <bodyTmpl>Namespace_Module/product/sku</bodyTmpl>
            </settings>
        </column>
    </columns>
</listing>

Namespace/Module/view/frontend/web/js/product/sku.js

define([
    'Magento_Ui/js/grid/columns/column',
    'Magento_Catalog/js/product/list/column-status-validator'
], function (Column, columnStatusValidator) {
    'use strict';

    return Column.extend({

        /**
         * @param row
         * @returns {boolean}
         */
        hasValue: function (row) {
            return "sku" in row['extension_attributes'];
        },

        /**
         * @param row
         * @returns {*}
         */
        getValue: function (row) {
            return row['extension_attributes']['sku'];
        },

        /**
         * @param row
         * @returns {*|boolean}
         */
        isAllowed: function (row) {
            return (columnStatusValidator.isValid(this.source(), 'sku', 'show_attributes') && this.hasValue(row) );
        }

    });
});

Namespace/Module/view/frontend/web/template/product/sku.html

<strong if="isAllowed($row())"
   class="product sku">
    <span class="label" text="label" />
    <span class="value" text="getValue($row())" />
</strong>