[JdeBP]

Actually, extending it in a native Win32 way in line with the existing console model would have been quite a simple thing.

There are already CONIN and CONOUT objects. One simply needs to make the latter a synchronization object, the former already being waitable. The console screen buffer maintains a dirty rectangle of cells that have been dirtied by any output operation, be it high-level or low-level output. It becomes signalled when that dirty rectangle is not zero-sized, the cursor is moved, or the screen buffer is resized. And there's a new GetConsoleScreenBufferDirtyRect() call that atomically retrieves the current rectangle and resets it to zero.

With that, capturing console I/O is simply a matter of waiting for the console output buffer handle along with all of the other handles that one is waiting for, getting size/cursor info and clearing the dirty rectangle with GetConsoleCursorInfo()/GetConsoleScreenBufferInfo()/GetConsoleScreenBufferDirtyRect(), and reading the new cell values of the dirty rectangle with ReadConsoleOutput().