Actually, Brazil does not have a Wii U eShop, but has a 3DS one (idk why, probably has to do with banks blocking international purchases in Reais in 2012 which had some conversion tax, thus not really as a national purchase... or something. Since the 3DS eShop opened before the block, Nintendo probably left it open, but decided not to open the Wii U one... or do what Sony and Microsoft did to prevent such issue). IIRC, I can activate codes bought on nintendo.com on my 3DS (which has a Brazilian NNID), so I wonder if 3DS Humble Bundle codes can't really be activated in a Brazilian 3DS NNID... I'll test it later.
And about Brazilians with Wii U, since you can have multiple users, just create a Canadian NNID and buy/activate there, hue