What comes to my mind is that, there are places there are constant electricity in Nigeria but few. But, the issue is to know if the electricity is cheap or not. But, there are two types of payment in Nigeria, the prepaid and the post paid. Using post paid, Electricity company in my state do not check Metre at all, thy calculate it based on how big companies and houses are, people can take advantage of this to mine Bitcoin or other crypto assets in Nigeria.
I am not sure about postpaid, it might not be cheap, but users have to calculate this on their own because the bills differ from state to state. I noticed we in my town paid less in electricity than people is another town. Because of this, it will be good for the person that want to mine bitcoin or any other crypto asset in Nigeria to calculate this on his own.
First by checking the watt the miners will consume
Also the watt others like cooling machines will consume during hot weather
Checking also the bitcoin paid by mining pool for the hashes generated for the miners he want to buy.
All thes will be used to calculate if mining is profitable in his area of location in Nigeria. Mining profitability will really differ from area to area.
About the issue if miners, I do not also think ordering from countries like China should be a barrier, but having retailers selling miners here in the Country will make them cheaper, getting it from abroad is not bad after the profitability calculation is made and positive.