VAYALT DC 24V 41.6A 1000W Switching Power Supply, 110V/220V AC to DC Converter, Universal Regulated Switching, 24V Power Supply for CCTV Camera System, 3D Printer, LED Strip, Computer Project

A POE switch is definitely one way to do it. If I were to do this I would just get 40 cheap DC to USB C PD adapters, a 24V power supply > 35 amps, 40 voltage+current monitor, and a coupl microcontrollers to monitor it all. The adapters say they're at least 92% efficient so at 20W*40 the box would dissipate no more than 64 watts (if the spec is to be believed) which could easily be cooled with a decent size fan. Edit: I noticed you said you need to turn off ports individually, you could use relays or power transistors for that.