Under the leaderboard tab, if the "Solution" column has an icon, it's clickable. 2nd place solution is by Jeremy Howard (of fast.ai fame), which I'd summarize as TrueSkill Through Time (Microsoft Research paper) + some overfitting on the public leaderboard (1st place was #26 in the public leaderboard).
https://www.kaggle.com/competitions/chess/discussion/107
There are plenty of rating systems out there that perform better than Elo.