It is possible to add support for wireless controllers to the NES through its unused expansion port.
Update your NES.
RetroTime has discovered an innovative way to utilize the expansion port that Nintendo included on the bottom of the NES, which was never used. Their new device, NES Hub, connects to this port and adds Bluetooth connectivity, allowing up to four wireless controllers to be connected to the nearly 40-year-old console.
Currently, the NES Hub is available for pre-order through 8BitMods for a price of $57.28, with shipments expected to begin as early as December 2024. The installation requires no soldering or hardware modifications, and it is not necessary to open the NES. This accessory easily plugs into the expansion port and is designed to fit perfectly in the gaps beneath the console. The most complicated part of the installation is connecting a small Bluetooth antenna and sticking it on the back of the console, which seems quite straightforward.
With support for up to four Bluetooth controllers, the NES Hub replicates the functionality of an accessory that Nintendo released in 1990, known as the NES Four Score, which also allowed for the connection of up to four wired gamepads. Although only around 25 NES games were compatible with four simultaneous players, all of them will work with this new accessory.
Additionally, with an optional adapter, the NES Hub can be used to connect Super Nintendo controllers to the NES. It also includes a special mode that "allows some Famicom games to utilize more audio channels for a better sound experience," and features three additional ports for connecting other peripherals. One of these is a $26.03 add-on that enables the use of Super Nintendo gamepads and accessories designed for the Japanese Famicom.
When connected to a PC via Bluetooth, instead of a controller, the NES Hub offers a web-based configuration tool accessible through Google Chrome. Users can reassign controls and buttons, and even switch to a keyboard and mouse mode if they believe it will give them an advantage when playing Super Mario Bros.