foreach (Button button in GetNode("Menu/CenterRow/Buttons").GetChildren())
{}
But it will throw an exception if not all children are a Button, if you need to check if the node is a Button then use this:
foreach (var obj in GetNode("Menu/CenterRow/Buttons").GetChildren())
{
var button = obj as Button;
if (button != null)
{
GD.Print($"{button.Name} is a button");
}
}
Another safe assumption is to cast to Node:
foreach (Node node in GetNode("Menu/CenterRow/Buttons").GetChildren())
{}
It depends if you need to use button functionality or not.