Apple added a new iPhone app with iOS 12: Siri Shortcuts, which uses Siri to simplify your life. With Siri Shortcuts, you can create customized shortcuts to things you do every day, which can be accessed with the tap of a button.
The good news for HomePod owners is that you can activate Siri Shortcuts on your HomePod, too. If you create a custom shortcut, you can ask for Siri to perform it using HomePod.
Here's how Apple describes one possible use case:
"For example, create a Shortcut to order your favorite coffee drink each morning. Or something more complex such as a good morning scene, where your coffee is ordered, your window shades lift, lights turn on, and Siri tells you about your first meeting of the day — all with one simple command."