I don't think so, but I'm not positive. But with as hard of a shell snails have I'd assume it would be WAY to hard for them to digest let alone chew. Also the snails may have a lot of parasites depending on where you found them.
Yes you can use them to feed your Cham but you have to breed them out a generation or 2 to get rid of the parasites. And you should gut load them and feed them when there young so the shells are soft. Here's a good blog that sandrachameleon has explains everything you need. Hope this helps
Get a bin or aquarium and put some organic soil in the bottom. I mix in about 25 percent sand. Keep the soil moist. Put the largest snails in there and they will mate and lay eggs. I then remove the eggs to a new bin and discard the old snails when you're done with them. The babies will hatch in approximately two weeks. I feed mine romaine lettuce,carrots and such.