Setup, as I understand above screenshot, for related “magic device” (Device 3 = Nexdock360) should be the very same as shown here (there exist only one USB-C port on N360 that supports DisplaPort, yet please correct me if I’m wrong):
Second option for the same Device 3 = Nexdock360 would be USB-C to HDMI Adapter (for example: www.aliexpress.com/item/1005002012736689.html), actually both related ports that you plan to be used with this “magic device” are placed on the left N360 side.
And, as hopefully clear from the screenshot above, only device that would get powered from is Librem 5, getting power from its original power supply as 5V/3A. Charging USB-C port for Nexdock360 is on the right side of this device and I have no clue which voltage/power it consumes, as those numbers probably quite irrelevant here, IMO.
Sorry for this late reply! EDIT:
Baseus GN16A dock USB Type-C female port (entrance port for 5V/3A or feeding port) you can still connect to the bottom right side USB-C data port of the N360 and continue using it with the rest of there connected devices (minus Librem 5).