I don't think the world itself is an illusion, how we perceive and experience it is. We perceive the world based on the 5 senses of the nervous system. If a watermelon is in front of you, that watermelon physically exists, but how your nervous system perceives it is the illusion. What would a watermelon be if you only had the sense of smell but couldn't feel see or taste it? What would a watermelon be if we had more than 5 senses? Look at a building brick. We can experience it with our 5 senses. We know we can build with it, throw it, trip over it. How does a dog experience a brick? It's nothing to them. Just something to briefly sniff or walk around. Would the brick still be the same thing if we had more nervous system senses or a far greater level of intellect to experience it? What would this brick be to us then?