This is a list of bits of hardware and at this point is targeting Linux but this really can cross platform category.
In my post childhood gaming, the PlayStation style controller became my go to, but now I must say that the Wii U Pro Controller is my favorite to use for gaming. It is not only Bluetooth but just feels great to use for modern and retro gaming.
It is indeed still possible and easy to use a 3.5″ Floppy in Linux.
Turn your USB into a DVI or SVGA output. USB 2.0 is a bit on the slow side but doable.
Resources Tagged for using openSUSE (and others) on a Raspberry Pi