Google has just announced a new developer preview for Wear OS, which it says brings Android P platform features to wearables. It includes a number of additions, such as a dark system theme, limited background activity, radio deactivation when the watch detects it's not being worn, and so on. Downloads are available right now for the Huawei Watch 2 Sport and Classic.
The blog post highlights a number of new features. A new dark system UI theme will probably be the biggest visual change; Android Wear 2.8 added it, but it'll now be the default. Google says that this is to improve glanceability, and I'm sure that many of you will be happy with this. To conserve power, apps will no longer be permitted to run in the background unless the watch is being charged. Of course, this won't apply to watch faces and complications that are currently being used.
Additionally, Bluetooth, Wi-Fi, and cellular radios will now be disabled when the watch detects that it's not being worn for an extended period of time. Watches will also no longer automatically connect to Wi-Fi when disconnected from Bluetooth unless an app requires a high-bandwidth network or the watch is being charged. As for developers, non-SDK methods and fields will begin having their access restricted in an attempt to improve app compatibility, so Google is warning them to prepare to migrate from those.
All of these features, save for the dark UI, will roll out gradually. Downloads for the Wear OS preview are now available for the Huawei Watch 2 Sport and Watch 2 Classic, and there are separate images for China. System images are also live on the Android emulator. There are some known bugs that you should read about in the release notes if you intend to flash this.