I’ve created a working solution to control channels with a Google assistant thanks to the new channels HTTP API. In order to do this you need to expose the port 57000 of the AppleTV/ AndroidTV/Fire TV device to the internet via port forwarding.
In addition to this you also need iftt. Create a recipe and for +this add Google Assistant.
Add the things similar to my options on the screenshot #1
The “#” part will be the number you need to say and gets send via a POST to channels.
That sentence means “Switch to channel #” and you can just say “Switch to channel 5” and it sends the channel number 5 to the API.
For the +that recipe add a webhook and set it to POST. The URL needs to be like this :
Then save it and it should already work. Go to your google assistant and try to switch the channel. I have not tested the english sentence “switch to #”, but maybe google has that already reserved for google itself. You could then maybe use “ask channels to switch to #”
If you have any questions let me know