Can't think of a good username? Mine it! Has been tested on Ubuntu 20.04 LTS.
Takes a word like "cafe" (must be hex-compatible) and then generates numbers which get added to your word and hashed using SHA256 and KECCAK256. If the result contains the word "cafe" again in both outputs you have found a cool username. You can find even cooler usernames by toggling a bool value to true, then the result must contain your word at least TWICE in BOTH hash outputs. Have fun!
The only feature I cared about was multithreading, so the program checks how many threads your CPU supports and then evenly splits the input space among those threads. They don't call me MultithreadMaestro for nothing!