I have to be honest, I’ve never heard of an Echo device collecting data or reporting back to Google. An internet search reveals that you can manually add a Google Assistant “skill” to Alexa but that it takes some mods and workarounds.
Are you confusing the Echo device with the Google Home one?
Amazon only stores voice input after the wake word has been uttered (ie “Alexa”) and then stops when the task has been completed. Google got in trouble when they first sold the Home device because they were recording all the time. They have since modified the device to only record after the wake word has been uttered and then stops after the task has been completed.