Frogs hit any thing that move, would have to be small frog. If doable, I haven't looked into this. I did use to keep whites tree frogs with a Jungle Carpet python.
I wouldnt, theres a lot of balancing that needs o be done, they could hurt/annoy each other and chameleons are finicky as is seem like a big risk especially in a 20 gallon theres not much room for error.