Nintendo MyRewards vary from region to region. I’ve taken the time to compile a small list of free (and some redeemed) wallpapers offered on the Japanese Nintendo MyRewards website that wouldn’t be normally available in North America. You can download the wallpapers [here](https://drive.google.com/drive/folders/1i3ekTOz15jJKq524KDUoFSZzjZOh4hQB?usp=sharing).
Unfortunately, Nintendo seems to only offer a max resolution of 1080p wallpapers for their desktops but a plethora of resolution for mobile.
Edit: My personal favorite wallpaper from the bunch, Origami King. https://i.imgur.com/vXanTDi.jpg
Edit 2: Redeemed some coins and added Metroid wallpapers. Enjoy!
Edit 3: Pikmin is my new favorite now. https://i.imgur.com/h88ckK1.jpg