Personally I don’t in my extension
Instead I use a form input text field to ask the user their preference
As most users will ask you to use a different email address to the one attached to their Twitch Account. Or don’t want to grant elevated permissions.
It’s also a little nicer as a) you don’t have the second authentication loop and b) you can tell the user at point of data input how you intend to use the data (great for GDPR)