Migrate island to new Switch AND new Nintendo account?

My wife and I shared a Switch for years, now she’s getting her own. We also shared a Nintendo account, but now I’d like to setup a separate account if it’s not too painful. I’ve read about the transfer tool, and that looks pretty straightforward… If she logs in to the new switch with a new account, will she be able to link the island data to that account? Or is the island data tied to the account as well?