USB-PD hubs are very annoying. Devices with no battery on a hub (Raspberry Pi etc) will just get hard rebooted if anything else gets plugged into the same hub. I looked at a lot of hubs and they all behaved this way. They all cut power to everything, then re-negotiate the power allowance each device gets from the shared wattage, every time anything new connects. I could not find a hub that honored existing power contracts and gave new devices the remainder. My guess is the average customer expect the newest plugged in device to get max power (at the expense of everything else) or they return it to the store thinking it's broken.