Technically, even an optical port can deliver power. Light is just a particular form of electromagnetic wave that just happens to use another method of transmission (and you might need a different mechanism to transform its energy), but it also has an intensity, potential energy and resistance in the medium of propagation.
Signals aren’t magic, they consist of electrical power. You can get at least a little bit of power from anything that isn’t an optical port.
You cannot charge a phone off “a little bit of power”.
Technically, even an optical port can deliver power. Light is just a particular form of electromagnetic wave that just happens to use another method of transmission (and you might need a different mechanism to transform its energy), but it also has an intensity, potential energy and resistance in the medium of propagation.