Google has been working on its capability-based OS Fuchsia for at least six years. A few days ago, Fuchsia started rolling out to Nest Hub devices, thus marking its official release.
Google is not making a big announcement of Fuchsia launch, but confirmed the news to 9to5Google:
Google has told us that as of today, an update is beginning to roll out to owners of the first-generation Nest Hub, first released in 2018. For all intents and purposes, this update will not change any of the functionality of the Nest Hub, but under the hood, the smart display will be running Fuchsia OS instead of the Linux-based “Cast OS” it used before.
Google Nest Hub is device provided with a touchscreen display that can be used to control smart home devices. Previous to the update to Fuchsia, the device used a Linux-based OS running the Google Cast protocol. Fuchsia, on the contrary, is not Linux-based and includes a number of specific components.
Fuchsia Kernel is called Zircon and is written in C++. Zircon departs from Unix-like OSes by not supporting Unix-style signals and replacing fork and exec through the launchpad library.
Other components that make up Fuchsia are Garnet, which provides services common to all OSes for software installation, administration, communication with remote systems and so on; Peridot is a framework for composed, intelligent, and distributed user experiences; Topaz augments system functionality by implementing interfaces defined by underlying layers and exposing them as modules, agents, shells, and runners.
Fuchsia is not tied to a specific language and supports a variety of languages and runtimes, including C++, Web, Rust, Go, Flutter, and Dart. Dart and Flutter enjoy a special status, though, since the Nest Hub display experience was based on them and are being leveraged by the Fuchsia update.
InfoQ has covered Fuchsia since its public repo was first spotted in 2016 and the OS was still surrounded by an aura of mystery and believed to be a replacement for Android. Four years later, Google opened the project to external contributions while retaining control over its evolution. At some later point, Google removed all UI components from the repo.