These are Technicals. They are mobile, fast, cheap and reliable, and you can put all kinds of things on them. If the other side doesn’t have heavy weapons you can do a lot with that and even if they are maybe then too. The Brits showed this really well starting with Land Rovers in North Africa and plenty of folks have borrowed, improvised and improved on the idea over time but the basic idea remains.

Armour is often added locally, so long as the drivetrain, suspension, and chassis can handle it.

No, I did not forget to mention brakes. Upgrading brakes is a distant fourth to upgrading the drivetrain, suspension, and chassis in that order.