Is this skateboard piece LEGO?
You were on the right track. This is a skateboard, but it is not a LEGO part. It's a Mega Bloks part, probably from set 9167 (X Mountain). The skateboard in the top right has a sticker that seems to match your description.



The wheels clip on to allow them to pivot back and forth. I can only assume that this is to give these skateboards a more off-road feel.