Quickly generate a (custom) cryptocurrency vanity

My needs: Quickly generate (custom) encrypted currency numbers, for example: mantissa 8888888, generated within 3 minutes. For example: mantissa ABCDabc, success within 3 minutes. The master of the Ethereum forum said that only by using the GPU to generate more than 100 MHz/s. Must be familiar with cryptocurrency private key, public key. I will give you the reference code