I just made a setup with an AP6-Pro running in my car trunk.
#1 8Port Alte Poe switch
#2 AP6-Pro
#3 Netgear nighthawk cellular Hotstop/router - one ethernet plugged into the router ethernet port for data and one ethernet cable plugged into PoE port and connected to router with ethernet to USB-C adapter that takes power from PoE to keep the routers battery charged.
I have the nighthawk set to join my home wifi as a client so when at home everything keeps going but it offloads the internet traffic to the home internet instead of cellular.