You know those so-called android boxes ? (Which you connect to your TV, pretty much like a gaming console)
Imagine having this connected to your TV / Monitor , connecting a controller to that Android Box, they should work with the Xbox and PS4 controllers and connecting a XIM to that controller and playing with mouse and keyboard.
Even if the Fortnite devs dont want people to use controllers on the mobile game, there are still those android emulators for PC like Bluestacks which I promise you will add Fortnite support on day 1 when it is available for everyone.
Although I despise fortnite, the sheer ownage would be really satisfying. Playing with a keyboard and mouse vs touchscreen LOSERS HAHAHAHAHHAHAHAHAHHAHAHHAHAHAHAHHHAAHAH
YOU DESERVE EVERY BIT OF IT PEASANTS !!!!!