In the MCU, Wakanda has an embarrassingly bad military force, using pre-WW1 level tactics alongside weapons and armor that are massively ineffective relative the kind of technology going into them.

In this scenario, Wakanda takes their failure in Infinity War as a wake-up call that they need to improve as much as possible. They ditch the laser spears and literal cloth "armor" and start focusing heavily on improving their military technology, tactics, and strategy using the rest of the world as a reference point.

Wakanda is given 20 years to improve before some kind of enemy force (such as another fictional empire, country, PMC, things like that) of your choice decides to try and conquer Wakanda. Whose the strongest that this new and improved Wakanda can successfully defend themselves from?