Include in your dashboard like this:
<div data-id="fullscreen" data-view="Fullscreen"></div>
It doesn't even need to be part of the grid, Dashing will happily initialise it anywhere on your page. It is invisible.
Once added to your page, Hit 'f' to enter fullscreen.
In order to perform the automatic key press you can use a tool called xdotool which is capable to emulate user inputs. The only thing to do for you is to call a script periodically which uses that tool.