Given that the exact same question is the current top post but for driving instead of transit, I feel this question was needed.
My answer: I saw some guys hooking up a Raclette Grill to the outlet in an otherwise empty German intercity rail waggon. They had it unpacked in one of these 4 person seats with a small table. No idea if that could work or if draws too much power from the board net. I just headed on to the next waggon.
On the buses I’ve rode, they have music players that can play music that hook up on one end to the radio and on the other end to a flash drive, with the flash drive containing music files, sometimes conjured by riders. And I pulled a John Maloney when I entered the picture.