Think of it like a connective layer. You will still need to run your Home stuff through Google to function best, but you can then have it forward its actions and commands to fake listening devices on your network, that can make it work with anything you like, or do more than that.

It's powerful. I haven't delved fully into it yet, but it's also a great way to marry various smart home garbage together without being locked into a system. Use zigbee, z wave, matter, hue, and wifi blubs and devices all together seemlessly.