You can think of this as an inline popup that can expand to take over the page, so a somewhat seamless redirect. But it doesn't do away with what you're asking

You can think of this as an inline popup that can expand to take over the page, so a somewhat seamless redirect. But it doesn't do away with what you're asking about; the redirect needs to happen, or a popup needs to happen. Portals can't be interacted with in the way iframes can, so OAuth worfklows will require going from your site to OAuth provider back to your site. > Also does it play nice with all of the intelligent tracking prevention stuff Apple is implementing? Having had the pleasure of dealing with it for OAuth workflows, I'd remove the 'I', and just call it Safari's TP.