You can use the renderer and rendererdetail system expressions to display that information.
The name of the renderer used to draw the game, currently either canvas2d or webgl. See Technology for more information on canvas renderers.
The name of the graphics hardware in use to draw the game, such as "NVIDIA GeForce GTX 660" or "Adreno 330". This is only available in WebGL mode in certain browsers and platforms; unsupported browsers/systems will return "(unavailable)". Projects should not rely on this string having any exact contents, but it can be useful to diagnose which GPU is in use in dual-GPU systems, or to look for keywords and apply default graphics settings based on the type of hardware.