No. Since the WiiU formats it´s own format (not Fat32). The WiiU DOES Support Fat32 only for SD-cards...but it doesn´t come with it´s own formating-tool dude.
Thus you need to format your SD-card via a (foreign) PC and/or smartphone/Tablet. The hell, some other gaming-console.
The WiIu only uses a propriatery Nintendo-format. The second you put in a new mass-storage it asks to format it and thus you cannot read it on a PC, since it´s garbled data (encrypted).
Sorry. There´s no workaround for that. You need a smartphone, with the necessary tool (and that means you have to use a unlocked smartphone, aka rooted) or a tablet. Some notebook/Laptop. Or a PC.
The hell- it doesn´t even matter how old your PC is. You can even use a Windows XP-PC if you have such an old machine. It would still work. You just need a Fat32-Tool.
Technically it would even work with a Raspberry Pi and a Fat32-tool lol.