Re: [EXT]Re: Beginner question: How to build meta post only

std300, please see:
https://tug.org/texlive/doc/tlbuild.html#Build-one-engine

The missing, and unfortunate, step is having to run a separate make to
build the engine (make mpost in your case) after the main make.

(I'm not sure if the special --disable-synctex --disable-xetex
--enable-missing is still needed, but they won't hurt.)
 
There is no need to disable everything individually, but you can get the
list from ./configure --help.

Hope this flies. -k