From https://github.com/sirdarckcat/sirdarckcat.github.io/blob/master/fakeauth/README.md

This allows you to control the El Gato Key Light Air through Google Home. It supports brightness and temperature.

You should be able to replicate this by:

1. Create a Cloud function at https://console.cloud.google.com/functions
2. Put cloudfunction.js on the cloud function.
3. Deploy the cloud function.
4. Create a Smart Home action at https://console.actions.google.com/
5. In fullfilment URL put your cloud function.
6. In the testing URL for Chrome put https://sirdarckcat.github.io/fakeauth/index.html
7. In the testing URL for Node put https://sirdarckcat.github.io/fakeauth/bundle.js
8. In device configuration add 3 scan configs:

* Scan Config:
  * mDNS service name: `_elg._tcp.local`
  * Name: `elgato.*`
* Scan Config:
  * mDNS service name: `_elg._tcp`
  * Name: `elgato.*`
* Scan Config:
  * mDNS service name: `_elg._tcp.local.`
  * Name: `elgato.*`

9. In the account linking, type placeholder in client name and client secret.
10. Go to tinyurl.com and create a shortlink for https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_CODE_HERE?code=1
11. Type the tinyurl on the Authorization URL
12. Type your cloud function on the Token URL

It has only been tested with one light.