If you link a Nintendo Account to Fire Emblem Heroes, you can do the following:
• Use the same user data on multiple devices.
• Back up your user data.
• Earn My Nintendo points, which can be redeemed for rewards.
• Playing on multiple devices using the same user data and backing up user data are possible between different operating systems. However, please be aware that Orbs purchased/obtained on the Android version of Fire Emblem Heroes cannot be used on an operating system other than Android.
• My Nintendo points will be stored in your Nintendo Account regardless of which operating system you use Fire Emblem Heroes on. However, My Nintendo points earned on the Android version of Fire Emblem Heroes cannot be redeemed on an operating system other than Android.