I'm also very interested in this technology.
I don't have much to add than the hope that projects like the new compiler and an eventual WL free microkernel might bring some extra "consistency" on this front.
And although a microkernel might not be reasoned as a core subset...:
microkernel => small footprint => microcontroller
eventually followed by
microcontroller => API call => whole set... (this line is obviously already possible, called from any microcontroller with internet access...)