Ideas are easy. You don't need to think of a new idea (in fact, I highly suggest not doing that). Instead, pick an idea that has been done to death and do it again.

Make a cronjob monitoring service. Make a "privacy focused analytics" platform. Make a session replay service. Make a "javascript error collection" service. Make a user feedback widget as a service.

It doesn't matter what you make. Pick something that has been done before and do it on your own.

If you are hell bent on live streaming-- live streaming that would be far more interesting than watching someone rebuild react.