Depends on the day I guess... Sometimes a S&W Shield 9mm, sometimes an XD-S .45ACP, but winter is coming so I'll rotate in a 686 CS-1 or my Kobra Carry.
Oh, wait! You didn't mean PROTECT my truck, but protection for my truck!
The 4th Gen workhorse gets Klasse All-in-One and two coats of Klasse Sealant Glaze. I have been using Klasse for decades and it just works and does so at a great price point and easy to use! Use Mequiar's Final Inspection or Sonus Acrylic Spritz (or homemade version of it) after each wash.
The 5th Gen has paint protection film and Nanolex coating. I use the care kit that came with the coating deal.
303 Aerospace Protectant on tires, vinyl/EPDM weatherstrips and trim, exterior plastics, and the vinyl tonneau.
Stoner Invisible Glass on the windows.
Blue Coral shampoo to generally wipe down interior plastic surfaces (foaming shampoo is great for lifting dirt out of textured plastic!), clean carpet or clean cloth seats.
ONLY Folex for any dirt or stain on headliner.
LEXOL Leather Cleaner and Leather Conditioner on the leather.