Is it. I was curious, and the first google hit I came across was:

https://worldpopulationreview.com/country-rankings/most-dive...

  1. Chad - 0.8514
  2. Cameroon - 0.8426
  3. Nigeria - 0.8306
  4. Togo - 0.8118
  5. Congo (Dem. Republic of) - 0.8111

For example, in terms of language, Nigeria has 525 languages:

https://en.wikipedia.org/wiki/Languages_of_Nigeria

“Index value is the probability of two people selected at random from any one country speaking the same language. 1.0 is most diverse, 0.0 is least diverse.”

I leave the reader to judge for themselves whether that is a good measure to judge diversity as being discussed here or not.