Gold coins. You can give one gold coin for a victory and then minus one for a lose so you can check if their win rate is high
2.real life level.Some people have a different level in real life , you can make a button to change your real life level and can show it to other people
Also I don’t see why having a second, uncalibrated, effectively random rank would be helpful, especially in such a prominent location. I can only see that causing confusion at best.