USB Type C, properly configured, can provide up to 100W and also a means to connect a serial device using the basic DP/DM pair.
More here: How does a USB C port provide the power to charge laptops?
The reason PoE limits the power has to do with the magnetics: the core wires are quite small, smaller than then 24AWG that Cat5 uses, which can carry up to 2A or so per wire.
As it so happens, PoE has seen some upgrades and can now support up to 90W. More here: https://www.versatek.com/what-is-power-over-ethernet/