If you’re using your Primal Lightning address, just set it once in Primal and it will populate on all other clients. Your profile data is just stored on relays.

Plugging NWC into Amethyst is harder than it should be, though. The only way I know how to do it is to long press the ⚡️ button on a note and you’ll get this option where you can scan or paste an NWC string. Best if you copy it from Primal and use the clipboard button to paste it into Amethyst.