"Now, I have to figure out how to attach it to a handtruck to
"portable-ize" it."

Office Depot or Staples sells a dolly that is for making a file cabinet
roll-around-able. Maybe that would work, Just tie a lanyard to it and pull
it to where you need it. A hand truck would work if you need to cross
thresholds or curbs; just make some short chain links to attach the
compressor frame to the hand truck so you can tilt it back.