I have my Home Assistant Dashboard on a couple of tablets in the house. It would be super helpful and look great if I can hide the sidebar and header. This could potentially be configurable from a couple of places namely the dashboard view editor, the entire dashboard editor, or the user editor.
A further improvement to this could be to somehow undo the hidden UI elements to temporarily access settings or other parts of the system. This could be done in multiple different ways but here are some ideas. Double tapping on empty space on the screen, bottom right fab (floating action button), refreshing the page asks you if you want to hide the elements, etc.