Provide the ability to personalize the viewer's profile.
1. Wallpapers, avatars, profile frames, statistics, a store for customized wallpapers, avatars, and profile frames that will be verified.
2. Create a viewer calendar so they can record events and reminders about what they want to see, with notifications.
3. A showcase where your favorite streamers and the viewer's comments about their time on their streams will be listed.
4. Also, a link to the year-end summary as a small icon in this profile.
5. Allow streamers to create icons or small captions for their channel. (This would look quite nice in Twitch chats.)
6. If you make it possible for anyone to upload their own art to the store for frames, stickers, and other items, it would be paid for by those who buy, there would be ratings and comments, and that would be interesting. I don't know everything about Twitch, but if only streamers can create their own stickers, that would severely limit people's artistic opportunities.
7. Create a section on Twitch with categories that highlight a large number of new streamers and streamers who have significantly increased their viewership in a short period of time.
A lot can be made private or not private in the settings, and the more extensive and flexible the profile customization, the more insane it can be for people.