Let's try an experiment. Go to Tunein.com. It's a website where radio stations are streamed live from all over the world. Since Nigeria is in the world, our radio stations are also included.
Next, go to the Nigerian radio stations. Here's a shortcut to make your life easier: Nigeria Radio Stations on Tune in.
Then, just pick a random radio station on the list. Any one. Note the accent of the presenter or on air personality (assuming they are not playing commercials).
Repeat the process 5 or more times.
What were the results in terms of Nigerian accent versus American, British, etc?