From App Clip I want to use third party app for authentication, this will lead the user to switch from App Clip to third-party app. The question here is whether it is possible for the third-party app to return the user back to the App Clip?
Is it possible to switch back to App Clip from third-party app
Is Sign In with Apple an option to you? That is designed to work beautifully with App Clips!
If you're using third party login that isn't for that third party, you'll have to add Sign In with Apple anyways to conform to the App Store guidelines.
I'd also like to do this in an app. The app I'm building uses Spotify's API, so I need users to go to Safari to sign in to Spotify and authorise my app to access their data, then be redirected to my app via a redirect URI callback.