To add WordPress user as an object to Twig, use the following code:

add_action( 'integration-cds/twig/ready', function( $twigEnv ) { 
   $twigEnv->addGlobal( 
      'wpuser', 
      get_user_by( 'id', get_current_user_id() ) 
   );
});

After that you should be able to use wpuser object

<p>Hello, {{wpuser.first_name}}</p>
<p>Your roles: {{wpuser.roles | join (', ') }}</p>