one of the key asymmetrical advantages that the (imperialist) military superpowers enjoy is highly advanced air defense missile systems. these systems can intercept a fair amount of incoming projectiles, but they miss a lot too and are extremely expensive.
why not just send thousands of explosive drones in a big grid pattern into the sky, make them hover there and detonate the closest ones when the drone grid detects a missile passing through? the drone grid can intercept multiple missiles simultaneously, is self-healing, low-tech, and inexpensive.
this could allow 3rd world countries to massively level up their air defense capabilities, thereby increasing 3rd world power.