Immediately you posted at first, I have checked it and saw that Zimbabwean dollar is not devalued to such extent as naira, but it is the government that are controlling the price in a way to protect the foreign reserve, if citizens are importing more products, to help reduce the rate of foreign reserve depletion, the government will have no option than to devalue their local fiat currency. About how strong a Fiat currency is, it is no a matter of the price, it is the marketcap (people that are using it and to what extent they are using it).

Is dollar the fiat with the highest price? NO. Not even Euro, not even pounds, I remembered up to 2018, Kuwaiti dinar has the highest Fiat price in the world, is it stronger than the USD or Euro or Pounds? No. That is how you will compared naira to Zimbabwean dollar, it has nothing to compare with naira in the forex market.