Your Nest Hub and Hub Max recently improved their display's information density by using ultrasound sensing. Knowing how close or far you are, they can adjust the font size and level of detail they show in some circumstances. But starting this week, they'll become more proactive and use this same technology to serve you relevant info as you approach them.
Googler Ashton Udall explained how better accessibility and vision impairment were behind the team's decision to use ultrasound to tailor information density for users. When you're far away, the Hub and Hub Max show larger fonts, no buttons, and fewer details for timers, weather, maps, and media playback. When you approach, the displays switch to a more detailed view with actionable buttons.
Thanks to this tech, the Nest Hubs will start showing reminders, calendar appointments, and notifications when you get near them. This should roll out to users from this week onward. However, this feature doesn't mind privacy: Since Ultrasound can only detect people and doesn't know exactly who each person is, anyone getting close to the display can trigger them. It's not the same thing as the Hub Max's Face Match, which only surfaces personal info when it recognizes you.
The announcement's wording isn't precise, but it seems that the Hubs will simply switch from the ambient display to the homescreen when they see someone getting near. If so, it'd be the same thing as anyone tapping on the screen, except it happens more proactively. For those who have enabled personal results on their Nest displays, the risk to show personal info to others was already there, and for those who disabled it, there should be no issue.