“ So we only have one option: testing many combinations of junk data until we can find one that passes our criteria. “

I have a somewhat related interest of trying to find sentences that have low Sha256 sums.

I made a go client that searches for low hash sentences and uploads winners to a scoreboard I put up at https://lowhash.com

I am not knowledgeable about gpu methods or crypto mining in general, I just tried to optimize a cpu based method. Someone who knows what they are doing could quickly beat out all the sentences there.