This couldn't be a D+ show, it would have to be a long OGN or actual novel, but how about...
What if Wakanda revealed itself during World War 2?
The Axis pushed into Africa... and Wakanda pushed back?
So look at it this way... You have Germany and the Axis going ham in Europe, you got Japan doing evil Japan things and Pearl Harbor happens, you got USSR being big and scary, and then the USA joins the fray because they are pissed...
and then another super power reveals itself in Africa. They push the Axis out of African and then fall back to Wakanda.
So, at the end of the war... you have Germany and suh defeated, Japan nuked, and the two big guys locked in a cold war... but there is now a 3rd party involved (wakanda) that scares the shit out of them.
And now imagine one of the two gets an itchy trigger finger and decides it is going to wipe out the tiny little country in one shot... and Wakanda's tech deflects/destroys the nuke and goes "No."
Just saying, could be a fun novel lol