Can I set the labels in Inbox to show the number of unread messages?
I don't know if this is what you're looking for, but each label shows it's number of unread messages. The problem is, that it shows them after the name. So if the label name is too long, you won't see the number.

Also, the label name changes to bold if you have any unread messages in it. And there is an option in settings, that sends to the top of the list any labels that have unread messages.

Hope it helps.