What kind of stats are you looking to showcase?
The closest thing we have to a public leaderboard at the moment is the users page, you can sort by clicking the column headers.
There’s also a new Yearly Review plugin that is kind of an annual leaderboard feature: Discourse Yearly Review Plugin
If you’re comfortable with front-end development you can build your own with a bit of work…
Data is accessible to build a leaderboard, for example this is a JSON file with users ordered by the largest amount of likes received this week https://meta.discourse.org/directory_items.json?order=likes_received&period=weekly
This post is helpful for finding this type of data: How to reverse engineer the Discourse API