With the focus on movement in mind, I think I’d opt for something more in the style of Jet Set Radio, as it would be far simpler to program in a mechanic that can be baked into the player controls rather than having to create a new entity that would interact with both the player and the world. However, adding grindable surfaces would post its own challenge, as it would likely altering the base game’s logic with how it interprets a player colliding with edges, corners, and flat vertical surfaces.