I don’t think we have any information about the software features it will bring. The main advantage with Android 10 is power management, security and compatibility.
Android suffered a huge change in the transition from 7.1.2 to 8.0. It was important enough to require a new kernel binder, and a lot of apps needed to be updated in order to function correctly (this is not completely true, but just so you can understand the advantages).
This means that now, with Android 10 we will be covered for a long time when it comes to app compatibility, as I don’t think Android will make any important changes like this one anytime soon. Android 10 also comes with native dark mode, which is very useful in AMOLED watches, and simulates the Android Wear experience a lot better.
Another advantage is the native gesture navigation, for which most apps are optimized. This means that you won’t get random “back” presses when swiping through an app, it’s now needed to do it from the edge.