I would guess they are probably technically illegal everywhere, as they are an obstruction to the 3rd brake light. When I installed mine I was actually a little surprised that it covered so much of the light. But, I would also guess it's probably a fix-it ticket, like tinted windows.

As for other vehicles. Not yet, but this one didn't exist until I emailed him about it. Took him quite a while to make them - I found out later he got married and was on his honeymoon. But it looks like he's selling them quite well (I should get a commission!), so you might want to contact him and ask for a Civic version. Just look up this one on eBay and you'll be able to contact him.