Quick question: is it best practice to use setters and getters ($Node.show()) or just directly change the variable ($Node.visible = true)?

I think the best practice is to directly change the variable, at least based on the C# code which warns that the getter and setter functions are “deprecated” and that accessing the properties directly is recommended. (Ultimately, I think it does not matter too much though, as the setters and getters are used internally in the C++ code base for accessing the variables and exposing them to GDScript)