There are several ways to do this, but here's how I would go about it:
Make a vertical and/or horizontal slider node and place them as a child of the camera. Set the min and max values to the min and max positions of the board edges. Connected the 'value_changed(value)' signal to a script. When the value of the slider(s) change, move the camera's vertical/horizontal position to the value of the vertical/horizontal slider.
That's just one way to do it. Another way would be using the scroll container like you mentioned though I've never used them so I'm not sure on the way to go around it.
I'm not totally sure if what I wrote above will work, and there's probably a better solution to the problem, but that's what I'd try if it were me.
