If we imagine that not all doors have the same state when you start up the game for the first time, you can go through all doors with the “Get All Actors from Class” node, then use a Map (Array that stores Keys with Values, in your case a unique Door with a boolean value) to store the state of each doors.
You can go through that easily with a “For Each” node.
Then on loading you do the reverse process, get your saved Map and use “For Each” to retrieve each door status.