Around here it's quite easy to get nitrocellulose based paints and clears!
They are used to paint lots of stuff like steel fences, gates and such they are one of the cheapest paint types available around here. There are a few body shops that still use it but most of them nowadays use urethane or acrylic enamel based paints and clears.
Here is tech sheet for a nitrocelluse clear, it's in portuguese so it won't have any interest for most people around here... But it's kind of a way to probe that it still exists and it's legal.
If someone wants I will translate it and post here.
And sorry for any incorrect paint terminology that I've used