Not only can Apple's HomePod be used to control HomeKit devices, but it can take the role of a HomeKit hub, allowing for access and control of compatible peripherals from outside the home.
The HomePod is third class of device that can act as a HomeKit hub. The HomeKit hub feature was previously limited to the Apple TV fourth generation and newer for all HomeKit functions, or an iPad capable of running iOS 11.
What you can and can't do in HomeKit without a home hub
Without using an Apple TV, an iPad, or a HomePod as a home hub, you can organize devices together in a room, control accessories, and create a scene to control multiple accessories with a single tap when you're in range of your wireless network.
Just using an iPhone will also allow you to control these devices, rooms, or scenes with Siri.
Activating your devices manually outside of the home, sharing access to your HomeKit setup to other users, or setting up a series of HomeKit responses to do something at a certain time of day or in response to a stimulus from a sensor requires a home hub.
The third generation Apple TV can be used as a HomeKit hub, but it won't be able to be used to remotely access HomeKit cameras, change user permissions, or create automations from the device.