The goal here is to guess private keys that are already in use. The rule is that there are no rules about what you should use as a random generator.

RTX 4090 is capable of doing 7.0 - 7.1 GK/s to scan a given range, not 4 or 5. Yes, just the keys in a given interval, not the ones with symmetry or endo (in that case, it can surpass 10 GK/s).