Modular is not in the player 
You can just make a BP that will do what you want. If you place 3 in the map, they will all work. That’s modular.
Also, once you learn about blueprint inheritance, you can extend the interactive object in a general way.
Sometimes stuff is in the player, like line traces for interaction, but that’s because it’s something the player is doing ( a bit like seeing ). With these interactives, your coding something the object is concerned with, that’s why the code goes in the object.