Have you ever think to use
Bisq?
It's a decentralized exchange with no authority over your funds. You just need to install the software, add your bank account numbers, deposit your bitcoins and start trading with people.
I have a thought on this mate, recently, Nigerian were stopped from using their bank(cards) in connecting with cryptocurrency transactions, however, their major means of purchasing bitcoin is through centralised exchange mechanism like Luno, Binance, remitano which all stopped operations with NGN cards transactions. Can bisq be used instead since they are decentralized platform with no authority over customers fund.
I will do some research either to check if Nigerians are eligible to connect with their bank account details.
Funny story I had an actual Nigerian business partner in real life, he was a doctor, radiologist, and on the side we imported cars. I sent over email my bank details to him, something I never thought I would do so it became a joke. But when I first met him I was very skeptical.