Electronics can be replaced. The Genny can be replaced. The entire underbelly of that rig needs to be removed and completely inspected for mold. All the wires traveling though the underbelly needs to be changed out. Moisture can get inside the wire insulation when it's submerged. Road splashing is ok, but submered is not.
Mold will grow in cracks. There is insulation under your rig. Mold can grow on top of the black/grey and fresh water tanks.
DO NOT let them just pressure wash the underside of your rig. Make sure they use the proper chemicals to remove and destroy mold. There are special companies that are set up to do just that.. An RV repaiman is not certified or trained in mold removal.
Obviously your brakes, brake lines and components of that nature were also submerged in water for a period of time. You leveling jack system as well to include the jacks.
WOW, there will be a tremendous amount of specialized work that will be done to your rig in order to get it back on the road.