There already are discussions about a category called "low%" where the player beats the world with every level finished with 0 coins, 0 badguys and 0 secrets.
In other worlds or versions it doesn't seem possible, so another way to look at it is that players can take the amount of collectibles they want and they will be ranked in ascending number of collectibles taken (and by quickest time for a same number).
Either way, for the category to exist, a devoted runner has to do a run of it ^^
1) Dying resets the collectibles count. Low% relies almost entirely on dying to checkpoints, that means that you actually need to collect a lot of coins (dolls are useful) before a checkpoint to be able to respawn at the checkpoint.
That's all I guess ^^ I've worked a lot on low% so if you need advice ask me here or on Discord.