Having Hardening means same haki? Yes they can both do hardening but unfortunately for you all hardening is not of the same strength. Jimbei and Who’s Who had hardening but clearly one was much better than the other, we know this from
And once again Same Techniques sure but the utilization of techniques is night and day.
If we go by your logic Everyone in CP9 was relative because they use Rokushiki.
You still don't get it.
You can't determine that one's hardening is stronger than the other unless there is a direct comparison. Therefore, at this moment, the only thing which is objective fact is that both have hardening. Claiming that Lucci has better haki is headcanon
Utilization of what technique. They have different fighting styles so they use their techniques to boost said fighting style. Lucci had his version of shigan and so does Kaku. Does Lucci have bigan? No so by logic Kaku would be better lol
Ahhh that's the thing though, my logic is that as we have it now, both characters have same tech, same haki and same awakening so claiming that one is two tiers above the other is headcanon