What is the real advantage of Google's new Fuchsia operating system kernel?
From what I understand you are asking what are the technical benefits of zircon over linux?

First of all zircon is a micro kernel as opposed to the linux monolithic kernel. So lets look at some of the advantages of an microkernel over a monolith:


Segmentation, a micro kernel has a very segmented model and drivers live outside of the kernel. That means you have more control over what those pesky vendors put into your kernel to slow it down. Security is increased because you can protect the core of the kernels functions from god knows what monster code the vendors wanna chuck in there as drivers.
Size, a micro can be way way smaller in size and together with the modularity of the micro kernel can help so you have the same kernel on everything from your phone, laptop to a IoT thermometer.
Speed, although in practice you have a lot of microkernels that are slower than monoliths because all the communication between the pieces of the kernel create a lot of overhead, you could have speedier communication with things like File I/O, network traffic and other components by the lack of context switching between kernel space and user space (think >10Gbps networks).
Control over updates. One of the biggest problem with Android is fragmentation, if you wanna build an app you have 839274326 versions of Android out there, for which version do you build your app? Also you have vendors not applying patches because they need to build their version with all the modifications they put in. If you had a really segmented core that you could update without affecting the vendor modifications that would be a big win for Google.
Real-time operation, they probably want a pure real time implementation because it goes well with their data collection needs.