? Open Apps
This one is pretty straightforward, but Siri will let you open any app that’s already installed on your device, even when offline. This includes Apple’s own first-party apps, as well as any third-party app by name.
Oddly, however, you can’t close apps while offline — you can only switch to another app, and of course asking Siri to “Open Home” takes you to the Home app, not the Home Screen. “Return to the Home Screen” tells you that you need to be online to accomplish this.