The USB port is 2.0, and there's ports of optical audio output, a headphone jack and antenna input. (cordcuttingreport.com)
One port notably absent (and sorely missed by some fans of previous incarnations of the Apple TV) is the digital optical audio output; fans of using their Apple TV units as music media centers have definitely made their opinion about the missing digital audio jack known. (howtogeek.com)
Roku reserved options like remote voice - search capabilities, a USB port and optical audio output for the Ultra model. (cordcuttingreport.com)