Return JWT token to javascript SPA from oauth login

I'm developing a javascript spa in vue.js which is going to eventually be a cordova application. As well as a backend api built with lumen.

I'm trying to provide login with facebook and google functionality. I've added the laravel socialite package and created a redirect and callback route. Ive created a page in my spa with the login buttons that direct to my api redirect. The user is redirected to facebook's oauth mechanism I login, the callback routes handle function looks something like this

public function handleProviderCallback($provider)
{
  $oauthUser = $this->socialiteManager->with($provider)->stateless()->user();

  $userEntity = $this->repository->findOrCreateOauthUser($oauthUser);

  $providerEntity = app()
    ->make('em')
    ->getRepository('Entities\Social\Provider')
    ->findOneBy(['name' => $provider]);

  if(is_null($providerEntity))
  {
    throw new \Exception('Oauth Provider not found');
  }

  $socialAccountEntity = app()
    ->make('em')
    ->getRepository('Entities\Social\SocialAccount')
    ->findOrCreateSocialAccount($providerEntity, $oauthUser, $userEntity);  

  $token = $this->auth->fromUser($userEntity);

  $resource = $this->item($token)
      ->transformWith($this->transformer)
      ->serializeWith(new ArraySerialization())
      ->toArray();

  return $this->showResponse($resource);
}

It basically gets a the oauth user, finds or stores them in the database, finds or stores their social account info,

$token = $this->auth->fromUser($userEntity);

Then authenticates them with JWT issuing a token. Which is then serialised and returned as a json response.

The problem is that the response is given while on the backend application, im never returned back to the javascript SPA.

Instead of returning json I could do some redirect like

return redirect()->to('/some-spa-callback-route');

But should the api be aware of the SPA location? and how will this work when the SPA is ported into cordova, as the mobile application wont have a url?

My thoughts are that A

The social provider should redirect directly to the SPA at which point it should make another request exchanging the authorisation code for a JWT token.

B it redirects to the SPA with a query string containing the token, which doesn't sound secure.

or c sends some type of cookie back.

And I am still confused as to how to actually redirect from my api to a mobile application.