I’m not sure that will work. Get all actors of class returns an array of Actors, not classes, so the entities actually have to EXIST in the runtime first to be collected by that node.
I think what you are looking for is an Object Library. At the moment they can only be used (though they can be created in BP) in C++. I would search the documentation for them, they will likely help with whatever you’re doing.
Create a simple array containing all classes by hand and alter it at runtimethe above methos just works for all Actor’s in the game of a certain class. If you do not spawn them they returned array will be empthy