Let me know if you find any useful resources on this as it’s becoming a bottleneck in my project for various different features. I’ve been looking for good solutions for a while now.
On EndPlay there is a parameter with an enum passed through as to the reason why the actor has been ended, EEndPlayReason::RemovedFromWorld is one of those reasons. I haven’t gone down the train of thought to apply this to solving this problem so maybe there is a solution here.
Though I would still prefer to just be able to get a OnCellUnloaded/Loaded callback from the world partition subsystem or something similar and be able to get a list of all actors within that cell.