Google has released android O developer rom based on android oreo. It is only available for google devices such has pixel phones and nexus devices only

FEATURES OF ANDROID OREO:
Notifications in Android O

Many of the new features regard notifications, and in Android O we will see user-customisable notification channels whereby alerts are grouped by type. Users will be able to snooze notifications, and devs can set time limits for notifications to time out. Also adjustable will be the background colours of notifications, and the messaging style.

Background limits

In Android Nougat Google introduced the ability to restrict certain app activities in the background, and in Android O it improves on this by placing the priority on extending battery life without user-input.

Improved Autofill Framework

Users will have to opt in to this service, but will then find it easier to fill in login and credit-card information forms with fewer mistakes and much less repetition.

Picture-in-Picture mode

Picture-in-picture, which is already available on Android TV, is coming to Android O. This is mostly used for video playback.

Improved keyboard control

Android O won't be restricted to phones, so there will be improved arrow and tab key navigation for when used with a physical keyboard.

Adaptive icons

Icons in Android O will support visual effects and can be displayed in various shapes on different devices. 

Connectivity enhancements

Wi-Fi Aware will allows apps and nearby devices to discover and communicate over Wi-Fi without an internet access point. We'll also see improved Bluetooth support for high-quality audio through the Sony LDAC codec, and new ways for third-party calling apps to work with each other and with your network operator's special features.

We discussed Android O in our podcast:

Multi-display support

Interestingly, Android O will be able to support multiple displays, allowing a user to move an activity to one screen to the next.

Better management of cached data

Every app will have a storage space quota for cached data, and when the system needs to free up disk space it will delete data from apps using more than their allocated quota first.

New enterprise features

Google says it has made the profile owner and device owner management modes more powerful, productive and easier to provision than ever, with highlights including the ability to use a managed profile on a corporate-owned device and enterprise management for file-based encryption.


We were already aware of a few user-facing features coming to Android O thanks to a tip-off from VentureBeat, though there was no confirmation that they would make it through to the final build.

Copy Less

This feature is expected to ease copying text from one app and pasting it within another by giving suggestions in the second app as to what you might be about to type based on what you were doing in the previous app. VentureBeat gives the example of finding a restaurant in the Yelp app, then opening a text conversation, beginning to type 'It's at' and the restaurant name popping up as a suggested term. It is currently unclear whether it will be a new feature on the Gboard virtual keyboard or baked into Android itself.

Opening addresses in Google Maps

Right now it isn't possible to share your current location on Android as it is in iOS, but according to VentureBeat there are some new changes coming that make dealing with addresses easier. If you click on an address in a text message, in Android N it does nothing but in Android O it could open that address in Google Maps. It says it is not yet known whether this will be functional only in Google's Messages app, or in all messaging apps on Android O.

Improved gestures

Today you can quickly call up your contacts using Ok Google, but in Android O you will be able to draw onscreen the letter C to open your contacts menu. This is similar to what we've seen in many Chinese phones - the ability to in standby mode draw onscreen a letter and open an app of your choice - though here it should work when the screen is switched on and in any app. This feature may not be ready in time for Android O, however, the source warned.

It will be released in August/September 2017 in US.
Now it is  only for preview, after August it will be implemented in all android devices
Don't no when will meizu release android nougat still it has not released marshmallow for all devices, hopping that meizu will work on Android updates.