For "blindsight" (like echolocation, being able to sense your surroundings even in darkness) wouldn't you just use Roll20's "Night Vision" setting under a token's dynamic lighting? That exists. I'm not aware of blindsight going through walls in D&D. For X-Ray vision (able to see thru walls), it would be cool if a Token could ignore DL walls. For Ethereal (able to walk thru walls), it also would be cool if a Token could be set to ignore DL walls.