It would be super silly and probably against every spec ever written, but I’d love to be able to plug a digital signage Raspberry Pi into a TV and not need any other cables thanks to Power-over-Ethernet-over-HDMI.
RPi4 should support power and network through its usbc plug, however you'll still need another cable for video currently.
the frame.work "SBC" would allow all 3 through the same connector, but, you'll be looking at ~400+ per SBC just to achieve this, but the key thing is, its 100% doable if you get the hardware combination right
The different bits will locally need a number of wires to join them together, but you might manage to run the whole thing off a single ethernet cable.