I am truly sorry for your loss.
But even Stevie Wonder could have seen there was a wiring issue here with that list of codes. Its not GMs fault the dealer couldn't get it to be checked out, or the dealers fault you don't have a vehicle back up plan.
Was that extended warranty(actually just an insurance policy) a GM backed warranty? Or aftermarket? - you might as well add this receipt to the list of items lost to your insurance company.
As mentioned before, get a replacement quote for the pickup from your dealer and dont settle with your insurance for trade in value because your not trading it in... Also gather any receipts for maintenance, anything you have put into the vehicle this will be added on top of the 1st insurance payout. Secondly get itemized list of your personal items and retail values of them to submit for personal belongings. That will be your 2nd insurance payout. 3rd will be person time lost ie vacation days or injury and possibly car rental fees.... Be ready to negotiate on 3 different claims. During mine I simply told them on the car value- you just find me a replacement that all I have to do is put gas in it and change oil to drive it 100 miles a day, like I was doing last week. Mind you this was a work car but I went from a 500 offer to 3500 after a few phone calls because I wouldn't settle. They will do this on your pickup too, just stand your ground and document any calls!!!! More later if your interested