Twitch supports two categories of notifications for users on their site: My Channel and My Twitch. My Channel provides updates related to broadcasts, such as subscriptions or donations. My Twitch provides updates mainly about game drops and other loot related activities.

I propose extending the My Twitch notifications so developers can send custom notifications to users directly on the Twitch platform. These notifications would act similar to drop notifications and would appear in the My Twitch feed. Users would have to agree to receiving notifications via oAuth when signing in or connecting their Twitch account to another application, similar to what many other platforms provide.

Notifications could include:

When certain parts of a stream are going live:
E.g. An esports tournament runs all day, but when the Grand Finals are starting the broadcaster has to stop then start the stream in order to notify all the followers of a channel. With API support for native Twitch notifications they could send out a special notice to all their followers about the Grand Finals starting without having to turn their stream off.

When large group activities are taking place:
E.g. A group of streamers are all taking part in a day of content, the streamers each have their own channel but work under a group that has a website where anyone can sign up. While each individual channel's subscribers can be notified when a channel goes live, this would allow the group to send out a mass notification to all users who had also linked their Twitch account via the groups website.

When users do not want to follow/subscribe:
If a user is only interested in a specific event or production that a channel is putting on as a one off, if they do not follow the channel they will miss out on notifications. If a user could request a notification for only a specific stream or set of a stream events instead of following the channel they could still be notified about the content they want to watch.