Google Smart Home integration with my IoT device (clarification needed)

I am looking for some clarification to how Google Smart Home works. I am looking to integrate my current end device which control lights with Google Smart Home.

My end device is running a very small microcontroller utilizing an RTOS (Linux is not available)

Here is how I see it (Please correct or comment)

To my understanding this requires me to host my own cloud service which will talk to my current end device?
My cloud service will then talk to Google cloud service.
My cloud service defines the protocol to talk to multiple end devices
Google Smart Home define the protocol to talk to my cloud service

Questions

Is there any method of doing this without having my own cloud Service?

Solution

That is a pretty basic summary of things - yes.

The crucial point there is that issuing a command to the Google Home does not have it send out a message on your local network. Google issues any commands from their network - not from your device.

This might seem like a minor detail, but it doesn't need to be a "cloud service" that you control that Google talks to. It does need to be a publicly accessible HTTPS endpoint. This could be a cloud service (and it would be in most cases), a public non-cloud server, or even just a public URL that has a tunnel to your private network (such as with ngrok).

The last is really how you'd get around having your own cloud service - you can setup the control on a local machine, and have a tunnel using ngrok.