Ah, I think you want to change the aspect ratio of the camera (the ratio of width to height), but this is a physical fixed value for each Google Nest camera; here are a few:
Nest Hello: 4:3
2nd Gen doorbells: 3:4
Nest Cam Battery: 16:9
Nest Cam Outdoor: 16:9
It has nothing to do with the Nest Hubs; they just display what's there.
The Ring doorbell's aspect ratio's are also fixed; for example:
Ring Video Doorbell Pro: 16:9
Ring Video Doorbell Pro 2: 1:1
The Nest Hub cannot display what is not there. While the Nest Hub has an aspect ratio of 16:10 (width to height), the 2nd Gen doorbells have an aspect ratio of 3:4. There simply is no content available on the doorbell's camera to fill the width of the Nest Hub's screen. The doorbell's camera can only provide a "portrait" view. The Nest Hello, with an aspect ratio of 4:3, is slightly different, and fills most of the horizontal space on our Nest Hubs, but if it tried to fill the entire horizontal space (with 16:12), the top and bottom would be truncated.
Consider that, when you configure Activity Zones, you are mapping out the entire physical area that the camera "sees".
With an aspect ratio of 16:9, when Google Nest cameras are displayed on a Nest Hub, there is a slight amount of black at the top and bottom as the view is displayed on the Nest Hub's 16:10 aspect ratio.
Everything that our cameras and doorbells see is being displayed on our Nest Hubs, with filler for what's not available on the camera
I don't think what you're asking for is physically possible.
Some Google Nest cameras DO have the ability to flip the image using the "Rotate image" that lets you flip the image by 180 degrees, in case you need to mount the camera upside down. This just flips the image upside down but does NOT change the camera's field of vision.
Google Nest doorbells have never had that "Rotate image" option, though a few customers have asked for it because they want to mount their doorbell upside down with the doorbell button on top for various reasons.
A handful of customers have asked for the ability to rotate their camera or doorbell image by 90 degrees, which is what you are asking for. I don't think it would be possible to rotate the camera's aspect ratio by 90 degrees; that's a fixed physical capability. This would involve using software to rotate what the camera is actually seeing.
Some Ring, Eufy, and Arlo cameras have the ability to rotate or flip the image by 180 degrees, but NONE by 90 degrees, though customers keep asking for it.
I too find this frustrating. My Nest Hello fills most of my Google Hub screen nicely at my house. I just installed the 2nd Gen Doorbell and a new hub at my mom’s house. The portrait 3:4 aspect ratio leaves a lot of black screen on the sides. She can pinch zoom the display but if she goes back to the Home Screen and the back to the doorbell cam, the display reverts back. Why would Google make this change (perhaps to work better with phone displays)? They should fix this to allow an aspect ratio change.
I suspect changing from the Nest Hello's aspect ratio of 4:3 to the 2nd Gen Google Nest Doorbell's ratio of 3:4 was quite deliberate on Google Nest's part, intending a more "head-to-toe" view. We're sticking with our Nest Hellos as long as they last. Here is what some reviews said:
"The Verge" says: "The camera captures a head-to-toe view with a 3:4 aspect ratio and a 145-degree field of view. These specs will disappoint those who love the Nest Hello, which has a higher resolution at 1600 x 1200, a wider field of view, and stronger digital zoom." - https://www.theverge.com/2022/10/4/23386060/google-nest-doorbell-wired-specs-features-price-release-...
This post on "Reddit" says: "Yes, the aspect ratio is actually one of the reasons I went ahead and got the gen 2. I can see my steps so much better now and that's where packages get left. It has been a big improvement in that respect." - https://www.reddit.com/r/Nest/comments/ysmmvt/gen1_vs_gen2_doorbell_aspect_ratio_what_was/
"TechHive" says: "Also new is the 1.3-megapixel color sensor with a taller 3:4 aspect ratio, allowing for a head-to-toe view of visitors as well as packages left on your doorstep." - https://www.techhive.com/article/1341019/google-nest-doorbell-wired-2nd-generation-news.html
"Pocket-Lint" says: "The Nest Doorbell (battery) has a 3:4 aspect ratio and a 145-degree diagonal field of view. It has a taller view than the Hello wired doorbell, enabling you to better see things on the floor in front of your doorbell, as well as people." - https://www.pocket-lint.com/smart-home/buyers-guides/google/157976-google-nest-doorbell-battery-vs-n...