Yes, the 4th generation Nest Learning Thermostat is compatible with Amazon Alexa. This integration allows you to control your thermostat using voice commands through Alexa-enabled devices such as the Amazon Echo, Echo Dot, or Echo Show.

To set up this functionality, follow these steps:

1. Ensure Both Devices Are Set Up: Confirm that your Nest Thermostat is installed and configured in the Google Home app, and that your Alexa device is set up in the Alexa app.

2. Enable the Google Nest Skill in Alexa:

Open the Alexa app on your smartphone.

Navigate to the "Skills & Games" section.

Search for the "Google Nest" skill.

Select the skill and tap "Enable to Use."

3. Link Your Accounts:

After enabling the skill, you'll be prompted to sign in with your Google account to link it with Alexa.

Follow the on-screen instructions to complete the account linking process.

4. Discover Devices:

Once the accounts are linked, Alexa will automatically search for compatible devices.

Ensure that your Nest Thermostat is powered on and connected to Wi-Fi during this process.

After completing these steps, you can use voice commands to control your thermostat. For example:

"Alexa, set the [thermostat name] temperature to 72 degrees."

"Alexa, increase the [thermostat name] temperature by 2 degrees."

"Alexa, what's the temperature in [thermostat name]?"

Please note that Alexa's control over your Nest Thermostat may have some limitations, especially when the thermostat is in certain modes like Eco Temperature or Off mode. Additionally, Alexa cannot control the thermostat if it's using Emergency Heat or if there's an Emergency Shutoff.