xyz Sadly looks like it isn't.
var prop: bool:
get:
print("You called?")
return true
func _ready() -> void:
print(prop if prop else false)
You called?
You called?
true
But prop gets evaluated only once if it returns false at least.
Although... thinking about it. This is a property with a getter so it makes sense that it needs to be evaluated every time. Maybe it only gets evaluated once if its just plain old data like an int or bool.