Uses the "demo store" notice to show a switch back link for WC customer accounts with User Switching: http://cloud.skyver.ge/c50cbcd4c5e7

user-switching-notice-for-wc.php

<?php
/**
 * Plugin Name: User Switching Notice for WooCommerce
 * Plugin URI: https://gist.github.com/bekarice/7785293fb60d7d5297a245b1c1271272
 * Description: Adds a frontend notice to switch back to your user on WooCommerce sites with User Switching.
 * Author: SkyVerge
 * Author URI: http://www.skyverge.com/
 * Version: 1.0.0
 * Text Domain: user-switching-notice-for-woocommerce
 *
 * Copyright: (c) 2019 SkyVerge, Inc. (info@skyverge.com)
 *
 * License: GNU General Public License v3.0
 * License URI: http://www.gnu.org/licenses/gpl-3.0.html
 *
 * @package   User_Switching_Notice_For_WC
 * @author    SkyVerge
 * @category  Admin
 * @copyright Copyright (c) 2019, SkyVerge, Inc.
 * @license   http://www.gnu.org/licenses/gpl-3.0.html GNU General Public License v3.0
 *
 */

defined( 'ABSPATH' ) or exit;

/**
 * Plugin Description
 *
 * Uses the storefront demo notice to show a "switch back" link for WooCommerce, as the 
 * WP admin bar will be disabled.
 */

// fire it up!
add_action( 'plugins_loaded', 'user_switching_notice_for_wc', 15 );


/** 
 * Class User_Switching_Notice_For_WC
 *
 * @since 1.0.0
 */
class User_Switching_Notice_For_WC {


	/** @var bool|WP_User switched user */
	public $old_user = false;

	/** @var User_Switching_Notice_For_WC single instance of this plugin */
	protected static $instance;


	/**
	 * \User_Switching_Notice_For_WC constructor.
	 *
	 * @since 1.0.0
	 */
	public function __construct() {

		// load translations
		add_action( 'init', array( $this, 'load_translation' ) );

		$this->set_old_user();

		if ( $this->old_user ) {

			// remove previously set store notice cookies
			// the cookie name won't change, WC core doesn't set it correctly by notice ID as of v3.5.4
			setcookie( 'store_notice', null, -1, '/' );

			add_filter( 'pre_option_woocommerce_demo_store', array( $this, 'filter_notice_option' ) );
			add_action( 'woocommerce_demo_store', array( $this, 'render_switch_notice' ) );
		}
	}


	/**
	 * Load Translations
	 *
	 * @since 1.0.0
	 */
	public function load_translation() {
		// localization
		load_plugin_textdomain( 'user-switching-notice-for-woocommerce', false, dirname( plugin_basename( __FILE__ ) ) . '/i18n/languages' );
	}


	/** Plugin methods ***************************************/


	/**
	 * Updates the store demo notice option to show the notice.
	 *
	 * @since 1.0.0
	 *
	 * @return string option value
	 */
	public function filter_notice_option() {
		return 'yes';
	}


	/**
	 * Updates the store demo notice messaging for our switched user.
	 *
	 * @since 1.0.0
	 *
	 * @param string original message
	 * @return string new message
	 */
	public function render_switch_notice( $message ) {

		$user_switching = user_switching::get_instance();

		$message = sprintf( 
			__( 'Ready to switch back to %1$s (%2$s)?', 'user-switching' ),
			$this->old_user->display_name,
			$this->old_user->user_login
		);

		$url = add_query_arg( array(
			'redirect_to' => urlencode( get_admin_url() ),
		), $user_switching::switch_back_url( $this->old_user ) );

		ob_start();
		// notice ID doesn't matter here, but leaving it JIC
		?>
		<p class="woocommerce-store-notice demo_store" data-notice-id="<?php echo esc_attr( time() ); ?>">
			<?php echo esc_html( $message ); ?>
			<a href="<?php echo esc_url( $url ); ?>" class="woocommerce-store-notice__dismiss-link">
				<?php echo esc_html_e( 'Switch back', 'user-switching' ); ?>
			</a>
		</p>

		<?php
		return ob_get_clean();
	}


	/**
	 * Set up the old user when switched.
	 *
	 * @since 1.0.0
	 */
	private function set_old_user() {

		if ( class_exists( 'user_switching' ) ) {

			$user_switching = user_switching::get_instance();
			$old_user       = $user_switching::get_old_user();

			if ( $old_user instanceof WP_User ) {
				$this->old_user = $old_user;
			}
		}
	}


	/** Helper methods ***************************************/


	/**
	 * Main User_Switching_Notice_For_WC Instance, ensures only one instance is/can be loaded
	 *
	 * @since 1.0.0
	 *
	 * @see user_switching_notice_for_wc()
	 * @return User_Switching_Notice_For_WC
 	*/
	public static function instance() {

		if ( is_null( self::$instance ) ) {
			self::$instance = new self();
		}

		return self::$instance;
	}


	/**
	 * Cloning instances is forbidden due to singleton pattern.
	 *
	 * @since 1.0.0
	 */
	public function __clone() {
		/* translators: Placeholders: %s - plugin name */
		_doing_it_wrong( __FUNCTION__, sprintf( esc_html__( 'You cannot clone instances of %s.', 'user-switching-notice-for-woocommerce' ), 'User Switching notice for WooCommerce' ), '1.0.0' );
	}


	/**
	 * Unserializing instances is forbidden due to singleton pattern.
	 *
	 * @since 1.0.0
	 */
	public function __wakeup() {
		/* translators: Placeholders: %s - plugin name */
		_doing_it_wrong( __FUNCTION__, sprintf( esc_html__( 'You cannot unserialize instances of %s.', 'user-switching-notice-for-woocommerce' ), 'User Switching notice for WooCommerce' ), '1.0.0' );
	}


}


/**
 * Returns the One True Instance of User_Switching_Notice_For_WC
 *
 * @since 1.0.0
 * @return User_Switching_Notice_For_WC
 */
function user_switching_notice_for_wc() {
    return User_Switching_Notice_For_WC::instance();
}