Hello, after some tests it seems very possible to use ethernet + poor man poe with no transformer, just solder directly
plain orange RXN
white orange RXP
plain green TXN
white green TXP
ethernet transfo is here by excess of precaution: every switch has transfos on it’s side.
plain blue+white blue: GND
plain brown + white brown : VSYS
on the opposite side, extract the blue/white blue pair out of the cable and the brown/white brown , and plug the blue pair to the negative, and the brown to the positive of a cheap 5v 0.5A (or even less) reused usb charger.
It works like a charm, as the milkv duo use very little power.
Note that as the spec describes, milkv duo VSYS can accept from +5V up to +14V. Not tested.
with this simple config you can have working connexion+power with only one cable.