Needed- Late model Dodge Truck AC help

Yeh, blocked and or moisture in system. so the bogus pressures were with guage valves open? You essentially had the compressor high and low sides open to each other.

It's not a TXV is it? They can go bad and "not operate" IE not pass refrigerant.
Did the system lay around "open" and absorb moisture? One way to combat that is to get the vehicle damn good and warm, engine "fully" warm. Run the cab heater to get the evap warmed up. "Flash some refrigerant through the system. Do that by leaving the low side open (hose off the gauges) and dump some refrigerant through the high side, it will go clear through and come out the low, hopefully flushing out most moisture. Compressor does not need to run for that. Then re-evaculate, with engine still "hot." That will help drive out moisture

Also running as you describe with gauge valves closed and that low evap, compressor should now short cycle on pressure switch