I came across the idea to use an SD card that forwards all traffic to an USB device or anywhere else. I haven't found any kind of hardware because I didn't know what I have to look for, but then I came across the official "SD association": https://www.sdcard.org/developers/overview/isdio/wirelesslan/index.html SDIO cards or iSDIO cards are exactly what I was searching for. For about $99 you can get an SD card that redirects the traffic to a wireless device / blootooth device or anything else and the other device is also able to send content back if authorized. The main advantage is that you can have unlimited space on the SD card, but it requires another device for communication. But does the Wii U support such devices? And what are the disadvantages?