Do you have any idea which locks are original to the truck? It appears that the door may have been replaced with one from salvage and the lock not switched.
If the door lock is original to the truck you could take your vehicle title to a Dealer and they could cut a key from a code they keep in the computer. You would then have two keys, but at least be able to open the door.
If the lock is not original it will need to to be removed to be re-keyed.
How to accomplish that would depend on a few choices, based on whether the truck is a daily driver or can be parked for a few days.
1. Daily driver: If you know someone that has some mechanical skills you could have them remove the handle assembly and replace it with a cheap one, without a lock cylinder, from RockAuto/Amazon. PN 25875521
. Then you would have a useable locking door. Same situation you have now. Then you could have the lock re-keyed without having the truck parked. Cost for that would be about $20 in addition to the locksmith charges. If you can't do the work yourself and don't know anyone that can help, an auto repair shop might do it. Then you have more down time.
2. Non-daily driver: Same as above, but you don't have to purchase a handle. Not positive, but you should still be able to lock/unlock the door with the remote if the handle is removed. However, the door would have to be opened from inside.
Note: Might be a good idea to contact a locksmith prior to doing anything and make sure they have the lock cylinder tumblers for your truck. The tumblers are not the same as GM uses for most of their vehicles. They could probably make a key to fit that lock, but re-keying would be preferable and not much more work for a professional locksmith.
Keep us posted.