Modanung originally the logic and level editor stored the exit area in a table, I commented and deprecated that way of storing the exit in favour of doing it directly on the grid by assigning a value for the exit area, which I think it's easier, I can still use the old system.
Currently the grid uses 4 values: 0 for empty spaces, 1 for walls, 3 for borders and 6 for exit areas.
The value 3 does not affect the logic, the value 3 acts like a wall but it draws differently, I created that value to let the drawing function draw a different type of asset for the borders of the walls in the maze.
So it seems like it's not difficult to implement, and even the theme matches the game.