For polishing out swirl marks or scratches on nitro, it's hard to beat Virtuoso polishes. They're pretty amazing, and that's what I use if my PS guitars need a polish, which is pretty rare, actually.
As someone else said, polish does remove finish - all polishes do. They're all abrasives. The question is how abrasive they are, i.e., how finely the particles break down when applied. Virtuoso doesn't leave fog or swirl marks, if you use it with a thick microfiber polishing cloth like these (don't use the thin ones):
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I've yet to get a swirl mark or any evidence of polishing using these, and I've been using them for a good ten years or so. Cotton will create swirl marks, even with a good polish, yes even old T shirts and diapers. Try rubbing a cotton cloth on something clear like a CD case, and then try it with a good microfiber. You'll see the cotton one hazed up the CD case pretty easily.
When using polish, light quick strokes are better than hard strokes, that will cause more swirling.
However, just to shine up the guitars, I like to use PRS' guitar cleaner. It's not a polish, and has no abrasives. It's also nitro-safe. I first clean the guitars with a damp microfiber cloth (not dripping wet, just damp enough to remove debris), dry them, and then follow up with the PRS cleaner on a clean microfiber cloth.
It's what they use at the factory before shipping the guitars to get them shined up. They look great. But often I just use the damp microfiber and a clean dry one, and skip the polish or cleaner altogether.
The less you abrade the finish, the better.