You read this here:
And it is sorta correct.
When we say headless launcher, we mean something that exposes the functionality of the current launcher (API, Access Management, etc) without the necessity to have a GUI or any window manager whatsoever. What exactly that will look like (as in the current thing “without the electron stuff” or changes in “safe_core” or maybe a different software altogether) is still up for debate once the RFC lands. I do have a draft but it needs a little more time before I can raise it for public debate just yet.