sadly you can't add :Array to an @exportnodepath
@export_node_path(Marker2D) var waypoints: Array
*this wouldnt work..
But you can do in fact.
@export var waypoints: Array
Then you get a NIL Entry, you can change the size of the array and with a click on the PEN, you can define what kind of Node it should be.. There you can select node_path and select your desired nodes. But doesnt work anymore in one script line..
Took me ages to figure it out as there is still no documentation for this.