The leaderboard API is only accessible for games that are officially on the catalog. People that want the leaderboard will not be able to “just go to the official site”. They’ll have to buy the online version.
So that would means 2 versions for the same game, where if a player bought the offline version, they wouldn’t be able to send their score.
Sideloading won’t mean having an offline version. For the merit of a game that use a leaderboard, it’s based upon the score and being competitive: You get to see your ranking.
As any player may, you can ignore that, and that’ll be your opinion, but it’s not the subject of this thread.