I’ve actually used this to my advantage. I bought some cheap speaker/light combos which basically made the lights dance to the music. The only power connector was a wire that comes straight out of the device and into an outlet. But it did have a USB port for loading music from a USB stick. So naturally I plugged one side of a USB A into the port and the other side into a power bank and it just straight up worked.
Doing this gives big bow to the machine energy for me, I don’t like it.