Can I Use an Apple Account to Link My Nintendo Account on Nintendo Switch?
Although you can create a Nintendo Account with an Apple Account, your Apple Account is not currently a sign-in option on the Nintendo Switch console. Please use a different sign-in method (email address or Google) to link your Nintendo Account to your user profile on Nintendo Switch.
If you have created a Nintendo Account with an Apple Account only, please sign in to your account from a computer or smart device and register an email address or link an additional service.