I'm not meatriding Sheckler with this, but someone as talented and connected as him to his skateboard, I doubt he had zero to do with the design. Was he Reynolds level involved? Don't think he went that far.
Interviews over the years have shown him describing features he wanted in his various shoes to meet his demands for skating impact but needing board feel, etc. Same thing with Ishod for his 2 pro models. Could that just be marketing in the interview clips we've seen? Sure, I'm not gonna rule that out either.