This is one of the first things I noticed about Lemmy, I agree that it's neat, but I too would like a way to see total subscribers, though I imagine that would be very difficult considering how federation works. For example, our total subscriber count would be fairly low, since it would only be the total subscribers of the instances who don't defederate us. It wouldn't count instances like beehaw, lemmy.ml or a number of other instances who have decided we are too problematic to stay federated with.