A week ago I shared about Google working on a new Photo Stack feature in Google Photos in my telegram channel. At that time there were just some strings inside apk, but with a new version v6.60 of Google Photos, I managed to enable the feature and I am going to share some information with screenshots and a video about it.
First of all, according to Google Photos strings - "Photo stacks automatically groups similar photos that were taken together." So basically it creates a stack of similar photos in your main "Photos" tab. This can help you in keeping your main feed clutter free. There are some things you can do with Photo Stack like pick a top pick photo and delete other photos from a stack.
Initially I though that this feature can group more than two photos in a stack, but in my testing I only saw two photos in a stack, not more than that. So it can only stack two similar photos and it will help you delete or pick the best one of them. I am not sure if this intended behaviour or anything will change in future. Update - It can stack more than two photos.
To enable this feature you have to go to Google Photos Settings > Preferences > Stack Similar Photos and turn on the toggle for it. The other way to enable it is - In the main "Photos" tab, tap on the three dots icon on top left which open a bottom sheet where you can enable it as well.
Once it's turned on, Google Photos will automatically stack similar photos together and you will see a stack sign on top right corner of the photo making it easily distinguishable from rest of the photos. When you tap on the stacked photo, a new page will open showing you the "Top Pick" pic (the same pic shown in photo feed) and a bottom bar with all the pics in the photo stack. You will also see a "Top Pick" text of top left corner of the "Top Pick" photo.
You can change the top shot photo by opening any other photo from the same photo stack, swipe up or tap on three dots on top right to see it's information - here you will see an option "Set as top pick'. From the same information bar, you can remove photo from stack with "Remove from stack" option. There is another option Google added in it - "Keep this, delete rest", which means you can delete rest of the photos from stack and only keep the one you are currently viewing.
Here is a full video of the feature in action -
I am not sure when Google will roll out this feature but I am sure it's coming within a week or two because the feature is working perfectly without any issues for me.