I believe you are asking how you could get the box collider to tell the button to set its visibility, if that’s the case, you can copy the following code:
Basically what this does, is you can use the get all widgets of class and get the first one (index 0) and call different functions and events from inside that widget with the output of the get node.
Does that make sense?
If you want to have something communicate with an actor, you would use the get actor of class node.
So basically you can create events/functions and directly call them from the output of the get actor/widget node.