It’s not an urban myth at all that Tom Paris was a renaming of Nick Locarno.
Kirsten Beyer (now a senior producer in the Secret Hideout shows) verified this point with Jeri Taylor (creator of Voyager) back when Kirsten was writing the Voyager Full Circle Treklit books. It’s covered in an afterward. Doubt that would have been cleared for publication if not true.
That said, whatever the meta situation, onscreen canon can be whatever the current EPs want. So, I’m curious where they’ve decided to take this.