What do you think, is Yung Lean a pioneer?

How big impact have he had on the scene?

yes

(unironically 'Kyoto' was super ahead of its time)

Don't know about pioneering but he likely inspired or at least made way for the likes of Trippie Redd, iann dior and Lil Peep (whom I personally most associate the "sad boy rap" music with).

Edit: And Juice WRLD of course.

Edited May 4May 4 by AllStarBySmashMouth