Even if you're not watching a specific repository, you can subscribe to individual conversations that interest you.
- In the upper-right corner of any page, click your profile photo.
- On your profile page, click the Repositories tab, then click the name of your repository.
- Click either the Issues tab or the Pull Requests tab for the repository.
- In the sidebar on the right, click Subscribe.
Once you subscribe to a conversation, you receive every notification thereafter, as though you were participating in the thread.