My idea is this:
You can get achievements just like retro achievements and you can earn XBOX gamer points like rewards that can be shown on things like the friend finder (other idea is a part of the website where you can look someone up and find their friend code for a couple of games like mario kart ds and wii message board) or you can buy things like they are nintendo platinum points like a wallpaper or a sticker that can be sent to your wii or the ds where you can trade stickers with other ds or wii consoles like collectibles or NFTs.
Wiilink only brings back WiiConnect24 functionality and makes country/continent exclusive Channels worldwide. E.G Food Channel which was only available in Japan.
Tho I think an own currency would be good, so they can spend them on Wii Room and if it ever comes the Everybody Theader Channel.