in the atari7800 version you can select the level,so an IL leaderboards could be useful to practice

Considering that that's an older console, and not everybody owns it, I don't see too many people running it.
I'm not saying its a bad idea though

if the IL its not convincing,then there could be a category called "finish maze" in the IL

I think adding IL’s for every platform could be a good addition. Especially for practice and figuring out theoretical times for 1-9 rounds and other full game runs. Pac-Man is a perfect game for IL’s since the previous rounds have no effect on the RNG of the current round.

there is many versions of pac-man that can load a level,so IL would be good (they would no be like 1,2,3,no,it would be like cherry stage,strawberry stage,and those) it would help practicing and can introduce more runners!