The question I want to ask is that many exchanges they are advertising I have not heard of the exchanges before, what are you know about the exchanges, are the exchanges safe to use to buy bitcoin true true?
They are local uncommon exchanges. I do not know how these local exchanges are operating but I can not recommend them because they are uncommon exchanges.
If they are operating in a custodial manner, I will not suggest anyone to go for it, if it is not your key, it is not your coin, and the most most important thing is that custodial exchanges can be hacked, if a reasonable amount ify trading volume are met, probably such exchanges can attract hackers and attempting hack, I can not yet trust such exchanges to be capable of resisting hack. It would be best to go for the ones that are more reputed like Binance or go for a decentralized ones like Bisq or Hodlhold.
Never see this as a way of not promoting our local services, but security first.
I suggest you use the popular exchanges like binance, Coinbase, roqqu, Patricia
I will not suggest Coinbase because they are not supporting Nigeria, the exchange is restricted and available only in few countries. For example, unsupported countries can not be able to take part in their referral rewards and other benefits. Coinbase do not support naira and Nigerians can not register on the exchange.