The monitor im using has external power, its a desktop model.
I have considered getting a portable USBC monitor for my laptop mount in my work van.
yeah, dual screen in vehicle! but now you mention it, those are probably PD powered.
also many of the USBC hubs with DisplayPort on amazon are PD as well. these hubs will do everything but DisplayPort without the Alt mode working. So if the NEW Alt mode dongle, lacked PD, it would drop that feature from the amazon hubs, and add frustration.
PD is gonna be helpful.