self contained executables simply bundles the libraries, but still requires a JIT compilation to execute.
The description of bflat is what you are looking for, and it's the second section of the readme.
bflat implements a form of ahead-of-time compilation.
This is closer to .net native conceptually, but that was only a UWP abomination.
edit: replies have pointed out this is actually closer to ReadyToRun, a neat feature I was not aware of.