For 2d/3d game better use DirectX/OpenGL libraries instead of canvas drawing
For controls, painting is done using canvas, so speed it limited. Yo can draw component to a buffer using DirectX/OpenGL surfaces (for complex compositions) and transfer to canvas control, using some buffering to avoid redraw
Forms and controls can be scaled from desing dpi to device dpi, check Handle.Scale from yout form
For test pixel perfect, I made a simple app to place a Button, Label and TRectangle to get coordinates & dimension of the shape (no style) to see if they are scaled some way.
TRectangle is positionated at (16,148) with a size of 64x64.
I run on my samsung galaxy tab, click on button to update Label text with the rectangle position and size and compare with screen shot.
Result, rectangle is positionated at 16,148 pixels in clientarea and is 64x64 pixels size, so no scaling has been done. Rectangle is show width 1 px arround the shape as desing.