If I clearly understand your question, you are looking for a platform where you can directly purchase BTC using your credit cards. If this is the case, you location will determine your platform of choice for such transactions. Lately, Binance exchange has made purchase of Btc with credit cards easier and fee friendly for countries they support, Recently they added the gateway for Nigeria at a very reduced fee. You can also check on them to see if they support such services in your country.