hiya, have you tried redirect_uri? That should work, but it will require you to configure the allowed redirect_uris in your FusionAuth application's OAuth config (on the OAuth tab in the admin ui). wildcards aren't recommended for the redirect_uri due to security concerns (see https://tools.ietf.org/id/draft-ietf-oauth-security-topics-05.html#rec_redirect ).
The other alternative is to pass a state parameter, which should be returned unchanged to you by FusionAuth. You could then have your code look at that parameter and redirect as needed.
You could also look at caching the value in localStorage and retrieving it after login has occurred.