From your post above, it sounds like you don't understand that DirectDraw allows you to get the raw frame buffer address, just as you have been doing with GAPI and with ExtEscape(GETRAWFRAMEBUFFER).

You don't need to use DirectDraw for blitting, page flipping, or YUV color conversion if you don't want to.

Create a DDraw primary surface, then lock it to get the pointer to the video memory that comprises the display, scribble into it, then unlock it. It's a pretty simple process.