Comment by int_19h

Very little, actually. You'd need CreateWindow to get a surface to render onto, and from there you have access to GDI, GDI+, OpenGL, and D3D via P/Invoke

If by "basic Canvas pixelData" you mean blitting an array of pixels in a loop, that would require a grand total of 4 API calls: CreateWindow, GetDC, CreateBitmap, BitBlt. Keyboard and mouse handling would be a dozen lines of code to process the corresponding window messages in the event loop.

I bet this would all still fit in under 64Kb.