Yes, it is possible to use GUI for all of the aspects of your game. Several games already have been made with Defold which do just that.
It should not necessarily hurt performance in any way - it depends on what and how you use features.
when a player moves a pawn to a certain tile, how to detect which tile it is?
You an either check cells within a virtual grid (similar to this Pixcade Cosmos ), or have tiles be actual GUI elements which you check if they have been clicked with gui.pick_node