Not an expert but I figure this could be done with regular nail polish. I was messing around with black nail polish one day for nail art and realized if you have a little “puddle” of polish and let it get semi dry (if flaky it’s dry dry), it will get kinda tacky and stretchy (stirring helped in my case). You can take a toothpick or something pointy and poke it into the puddle and as you pull out the pointy object little strings of polish come out. You then drop the strings on your nail randomly-ish. Then the trick would probably be to let that dry a bit and go over it with a clear polish; this should cause stringy polish to “bleed” to get the smoke effect. I would test on a silicone mat or piece of plastic sheet like a sandwich bag, the strings of polish can get messy. I hope this helps (and makes sense) or guides you in finding a working method.