Enlarge Image Derek Poore/CNET

Google Home and Nest Hub gadgets already feature microphones that are always listening for the words that wake up the Assistant ("OK, Google" or "Hey, Google"). Now, the search giant's newest gadget for your home, the Nest Hub Max smart display, adds in a camera that's always watching for a familiar face.

Google calls the feature Face Match, and it uses facial recognition technology to remember what you look like. After that, you can tap on the screen to see personalized bits of data like calendar appointments and Google Duo messages whenever it recognizes you.

The Nest Hub Max isn't the first product to bring facial recognition technology -- and the legal and ethical considerations that come with it -- into people's homes. Smart phones have been using the technology to let us unlock our devices and authorize purchases for years, and a growing number of smart home gadgets that use cameras are putting it to use, too, including Google's own Nest Hello video doorbell.

Read: The best facial recognition cameras of 2019

Still, it's a product that seeks to give Google a wider window into our lives at a time when the company is already facing questions about the way it handles our personal data. I wanted to take a closer look at how those privacy standards apply when you add always-watching cameras into the mix. (Here's even more about facial recognition in everyday technology and how to opt out.)

Now playing: Watch this: Google's Nest Hub Max smart display tracks your face

How private is that camera feed?

You'll start with Face Match by using your phone to scan your face, which creates a "face model" that the device attaches to your user profile. After that, when you're in front of the device and it recognizes you, you'll see personalized details like calendar appointments and Google Duo video messages from your contacts.

I had a lot of questions for Google about this feature, and about the camera's ability to spot a raised hand gesture in order to pause or resume playback, too. For instance: Is the camera always recording in order to process what it sees and spot familiar faces or gestures? Is it sharing everything it sees with Google's cloud?

"If camera sensing is enabled and the camera is on (i.e., not turned off via the hardware or software switch), then the camera is continuously processing pixels to look for faces and/or gestures," a Google spokesperson explained. "This processing is done locally on the device, and no pixels leave the Nest Hub Max."

Enlarge Image Screenshot by Ry Crist/CNET

You can also use the camera in the Nest Hub Max like a Nest Cam security camera, and view its feed at any time via Android TV or via the Google Home or Nest apps. If you'd like, you can subscribe to Nest Aware, a service that saves motion-activated video clips to a cloud account for you to review later. All of that -- watching the feed remotely and storing clips recorded from it -- involves uploading footage to Google's servers.

"When you are using your Nest Hub Max as a Nest Cam, and any other time when video or images are being uploaded to Google (for example, during a video call), you'll see the green light at the top of the device," the spokesperson said. "If you have subscribed to Nest Aware for your Hub Max, your stored recordings from the Nest Cam feature will be available for you to review and delete any time in the Nest app."

Google adds that neither the face and gesture tracking data nor the Nest Cam data is ever used for ad personalization, the company's process of using the data people share with it in order to target advertisements at them that are relevant to their perceived interests.

As for the data that does affect the ads you see, like the searches you make and your YouTube viewing history, Google lets you review its impact -- or turn ad personalization off altogether -- in the data and personalization section of your Google account.

Faces in the cloud

Google's representatives made a point of emphasizing the fact that the Nest Hub Max's Face Match and gesture-tracking features don't involve the cloud at all.

"Google's AI camera-powered features are happening on the device itself," said Ashton Udall, Google's product lead for smart displays. "When you do auto-framing in video calls, or when you do Face Match, or when you do Quick Gestures, all of that is happening on the device. We don't have to send things to the cloud in order for those things to happen. What happens in your home stays in your home with relation to these things."

That's good to hear, but when I began setting up the Nest Hub Max to test the device out, I saw the following disclaimer in the Google Home app:

"Face Match creates a unique model of your face that your Assistant uses to recognize you. This face model is stored on this Nest Hub Max and used to identify you when you're in front of this device. It's also temporarily processed at Google from time to time to improve the quality of your experience with this device."

Enlarge Image Screenshot by Ry Crist/CNET

I asked Google to explain that last line to me.

"The images you provide are used to build your face model, which is stored on your device," the spokesperson said. "However, we occasionally use the images you provide during setup to generate a face model in the cloud for a couple of reasons, all related to improving your product experience specifically on Nest Hub Max, and motivated by the fact that we have more computing power available in the cloud."

As Google tells it, those reasons are two-fold. First, the company says that when a Nest Hub Max has multiple users enrolled in Face Match, it may upload the face models to the cloud to ensure that each is distinct enough from the other to avoid false positives.

The second reason has to do with new features and facial recognition algorithms that may be coming in the future. When Google has one ready, it reserves the right to upload your face model to make sure everything works properly before pushing the new feature to your device.

"In all cases, if we ever process your face data at Google, it is only temporary, and all face models are permanently discarded," the spokesperson said. "You can always review and delete these enrollment images at myactivity.google.com."

Can I just turn the camera off?

Like the original, smaller-sized Nest Hub, which doesn't include a camera at all, the Nest Hub Max features a kill switch behind the screen that disables the microphones. Now, that switch disables the camera, too.

That's a step short of including a physical shutter that covers the camera entirely, a feature that consumers often appreciate with devices like these. Other Google Assistant smart displays, including the Lenovo Smart Display 10 and the JBL Link View made sure to include one. So did the Facebook Portal.

Enlarge Image David Priest/CNET

Many users prefer the sense of privacy offered by a shutter that they can leave closed when the device isn't in use, especially if they plan to keep it somewhere like a bedroom. Amazon seemed to figure that out in between last year's second-gen Amazon Echo Show smart display, which lacked a shutter, and this year's Amazon Echo Show 5, which added one.

When asked about the lack of a shutter, Google defended its design by downplaying the distinction between kill switch and shutter altogether.

"We've included a mic plus camera switch that electrically disables both the camera and mics, making it functionally equivalent to a physical camera shutter," said a Google spokesperson.

At any rate, the lack of a shutter seems to put a gulf in between Google and at least some of its potential customers, many of whom might be growing increasingly wary of just how much data they're sharing with Silicon Valley. Time will tell if the digital kill switch is enough of a compromise to bridge that gap.