Hi @donniekerr01,
you’ve probably found a solution a long time ago, but I’d like to share mine as it might help others struggling with this.
I’m building a Flutter mobile app and using the auth0_flutter lib to do the auth. To get SSO working, on iOS, I set the auth0 sdk to do the auth flow in a SFSafariViewController and then opened the web app that was supposed to use that session in a SFSafariViewController as well.
On Android, I ran the auth flow in Custom Chrome Tabs (the default in the auth0 Flutter sdk) and then the external browser (Chrome) did pickup the session.
Cheers,
Marcin