In other words I'm very lost and in over my head.
would you like a guide for windows with method 3?
methods 2/4 should work out of the box
still I recommend you to give a go to latest D (dmd or ldc2) with method 3
(2 may work too)
(personally I have both msys2 + and git-bash)
But I think method 3 is what you need.
BTW use UnigetUI (I configured with scoop/chocolatey/winget) to install cmake/jom
WindowsSDK, C3 (for the CRT) and clang-llvm you need to do by hand.
Then you are msys2-free
Maybe I need to do a dev-to/medium article for this.