The novelty is due to a newly released update that supports voice shortcuts. Thus, a command such as the traditional Ok Google or Hey Google can be recorded and, from then on, used to open the competition assistant.
If your phone is unlocked, you can combine two commands to trigger Google Assistant: Hey Siri. Ok Google. It may not be the most practical approach in the world, but it already improves the integration of the software into Apple devices. This, incidentally, has been an effort made by Google, which also already offers a widget from its assistant that can be added to the home screen or blocked display.
The update is also used for other shortcuts used in the Google Assistant. The user can, for example, customize a command to activate an action or an entire Google Home routine directly from Siri. The feature can be useful for those who have devices compatible with Google, but not with HomeKit, and want to access them via voice controls on the iPhone.