Speaking of passing through PD communications, I have a cheap Chinese power meter that sort of does that but not properly. Hopefully OP has a nice hub that does these things properly.

If you use a setup with a power supply, first cable, power meter and a second cable, you can measure things when connected to a chargeable device like a laptop. It obviously tells the PS to give it 12 V, which it will. Once you unplug the laptop from the second cable, the voltage reading doesn’t drop back to 5 V. Apparently the power meter doesn’t let the PS to know there’s no load any more.

As a result, you get a USB-C cable that gives you 12 V without asking any questions. Guess what happens when you plug in something that can only handle 5 V? Bad things. Don’t ask me how I know.

Anyway, once you unplug the power meter from the first cable, the PS finally gets the message and drops the voltage back to 5 V. Makes me wonder if a hub could behave the same way as my power meter.