> but Cygwin is a crazy approach, was slow

A lot of this is issues Microsoft could fix if they were sufficiently motivated

e.g. Windows lacks a fork() API so cygwin has to emulate it with all these hacks

Well, technically the NT API does have the equivalent of fork, but the Win32 layer (CSRSS.EXE) gets fatally confused by it. Which again is something Microsoft could potentially fix, but I don’t believe it has ever been a priority for them

Similarly, Windows lacks exec(), as in replace the current process with new executable. Windows only supports creating a brand new process, which means a brand new PID. So Cygwin hacks it by keeping its own PID numbers; exec() changes your Windows PID but not your Cygwin PID. Again, something Microsoft arguably could fix if they were motivated