Find someone with their bedrock. Works in the nether and overworld with nether roof and floor. Orientation does not matter all orientations get checked. It scans in a spiral pattern from 0 0 outwards. The mc version i used is 1.21.1 but it should work from 1.80 till now.
You will need openssl and linux. If you are on windows make a pr.
Fill out all the variables in settings.c with your desired values. And compile.
I got to 9millon coordinates per second checked. (CPU: i7) at x -25105 z -18996 running for 280s checked 2521000000 at 9003571.000000p/s