How to compile a program written in WL to a stand-alone executable file? Is this currently doable at all? If there is any on-going effort to enable this somehow (by Wolfram or any third party), any idea what's the current status of that effort?
You can create a CDF, which can run with the free of charge CDF player.
A very limited subset of Mathematica can be compiled into C.
That said, Mathematica is primarily designed for interactive work (i.e. evaluating inputs one by one, interactively), not for creating applications.