Fuschia could be the first new mainstream capabilities-based RTOS in 40 years. Plans and roadmap are unknown. However we can look at the program made via open source.
Seamless desktop/phone UI
In the video, Ron Amadeo from Ars Technica walks through all the stuff that is currently working on Fuchsia OS, at least on the Pixelbook. video
For a much, much deeper dive into the nuts and bolts of getting this up and running. See Ron's work including the installation streamed over a network page
More on Fuchsia: a new [capabilities-based] operating system contributed by Nur Hussein page .